Koga has dark red hair, and brown eyes. Whenever he doesn't wear his Cloth, he has red and white shoes, blue jeans and a white sweater with red sleeves.
His casual attire is replaced by a red outfit however as he equips his Cloth.
Koga may be considered similar to Seiya in personality. During battle, Koga is very serious and always gets back up if he's beaten down by his enemy. He is at times immature, making jokes about situations. He is also very caring for Athena and his friends. He is also quick to charge at his opponents, without thinking over the situation at first, usually leading to the young Bronze Saint being knocked down.
Statue of Athena
As a baby, Koga witness Mars arrive in order to claim Athena before a man in golden armor arrives to rescue his goddess. That man is the legendary Saint Seiya, the new Sagittarius Gold Saint. He watches with Athena as Seiya engage the god of war, equaling him in speed and strength although his Cloth suffers great damages.
Several years later, Koga is trained by Silver Saint Shaina at a secret island. However, he does not want to become a Saint unless he at least know what it is or being allowed to see Athena. He angers Shaina however when he speaks ill of Seiya, causing the Silver Saint to scratch him before he seemingly catch a brief glimpse of his Cosmo as he creates a crack on Shaina's headpiece.
As he later sleep on the beach, he has a dream about a man in golden armor. Remembering him as Seiya, he is surprised to see Saori and they talk about the responsibility of a Saint. Once more stating that he does not wish to become one.
Shortly after Saori gives Koga a necklace, Mars appears once again to capture Saori whom he reveals to be Athena. As Koga watches Athena burn her Cosmo, he bravely stand between her and Mars as Athena is covered in Darkness. Punching the god of war, Koga is simply tossed into some rocks before watching Shaina engaging the deity.
As she is defeated as well, Koga desperately attempt to break through the large wall of flames surrounding Mars before he succesfully burns his Cosmo and is acknowledged as a Saint, receiving the Pegasus Cloth. Urged by Seiya to burn his Cosmo, Koga attacks with the "Ryu Sei Ken" before being astonished by this mighty power. As Seiya informs him that this is Cosmo, Koga charge at Mars but is easily defeated.
As he watches Athena disappear, Koga is devastated and almost face certain death only for Shaina to intervene and take the blast herself. Blaming himself for this failure, he later promise Shaina that he will defeat Mars for sure and rescue Saori.
Awakening his element
While travelling, Koga meets Souma who teaches him about the elements. As they further travel, discussing Athena and Pallaestra, the Martian Ordykia ambush the two. Refusing to stand by and do nothing as Souma equips his Cloth and charge at his opponent, Koga finds himself unable to move due to the Cloth being to heavy. Unable to help Souma, Koga is wounded as the Martian turns his attention towards the Pegasus before Souma blocks the final attack, wounding himself.
Ordykia then unleash his "Dark Mist", easily gaining the upper hand against Souma while Koga states that he hates the thought of being unable to help anyone, having already failed once to protect someone. Remembering Souma's teachings, Koga is able to burn his Cosmo and awaken his light element, succesfully blinding Ordykia and allowing Souma to strike the Martian who retreats.
The two Bronze Saints then resume their journey to Palaestra where Koga will train and become stronger in order to save Athena.
Arriving in a forest, Koga is shocked as Souma states this is the Pallaestra before another Bronze Saint ambush him. To Koga's surprise, she is a female Saint wearing a mask which reminds him of Shaina, and she reveals herself as Yuna. Desperately defending himself, his bag is knocked away and he is amazed at seeing the female Saint's speed. Deciding to fight back, Koga succesfully equip his Cloth only for Geki to interrupt, stating that it was only a test to see if Koga truly was a Saint. He is surprised however to see Koga wearing the Pegasus Cloth.
New Pegasus vs. New Dragon
He shortly tries to leave in order to continue searching for Saori, but on the way, a young boy cross paths with him, stating that he is not yet ready, that his element has not truly awoken yet. As Koga is lectured by Souma, they also discuss this boy who Koga met earlier, realizing that he must be strong as he managed to use his element without wearing his Cloth. They later meet that same boy who is revealed to be Ryuho, the son of the legendary Bronze Saint, Shiryu, who fought with Seiya once.
While talking with Ryuho about Shiryu, one of the teachers named Georges catch the two Bronze Saints and is informed by Ryuho that Koga tried to escape earlier. Koga is angry as Ryuho tells at him, only for the Dragon to ask Georges for a duel between him and Koga in order to not get expelled from Pallaestra, as that is the penalty.
As the two Bronze Saints meet in a large building, Koga charge at Ryuho with several attacks, but Ryuho easily dodge every single blow. Stating that he feels Koga's attacks and has only need to move slightly, he begins to retaliate with his water element and gains the upper hand despite Koga's attempts.
Tired of being underestimated all the time and determined to save Saori, Koga burns his Cosmo and develops the new technique "Pegasus Flash Fist" which seemingly defeats Ryuho. However, he emerges with light wounds having blocked the attack with his shield. Facing his "Sho Ryu Ha", Koga is soundly defeated by Ryuho
However, Ryuho reveals that it was all part of his plan to help Koga master his element. Learning that Seiya and Shiryu once fought against each other and later became friends as Seiya saved Shiryu's life, Koga and Ryuho consider each other as brother-like friends.
As the Bronze Saints travel to a place known as Cosmo Delta, they are informed that they must reach the top of the mountain within sunrise, with dozens of dangerous obstacles in their way. To make things more challenging, Cosmo Delta drains the Cosmo if the Saints attempt to use it, so it will be deadly should they use their Cloths. Putting on his right bracers, he teams up with Souma before they are confronted by Argo who taunts Souma's deceased father.
As the Saints split up, Koga hears Souma's story about his father who was assassinated by someone wearing the same black armor as Ordykia. They are confronted by Argo once again who attacks Souma with his water element, leaving Souma to die as fire element Saints are not very good swimmers. Koga dives after and rescues Souma before they resume their journey.
They keep climbing until they stumble upon a gigantic wall of ice, said to never melt in a thousand years. Desperately trying to find a solution, Koga witness Souma in his Cloth destroying the wall of ice in order for Koga to pass through. Not wanting to leave his friend behind, Koga carries the unconscious Souma to the mountain where Geki expels Argo for having assaulted them earlier.
While Geki praise the Saints for having reached the mountain, he informs them that one Saint managed to reach the place first by traveling a path only Silver Saints have been known to survive: Orion Eden.
One day as Koga, Souma, Ryuho and Yuna discuss the future winner of the Saint Fight, he tries to introduce himself to Eden who arrives, but is only told to get out of his way. Yelling at Eden for being so rude, Koga is paralyzed by the Orion, collapsing to the floor. According to Souma and Yuna, Eden's element is lightning, and is thus vulnerable to wind, giving Koga the tought that Yuna can defeat Eden, although Koga wants revenge for what he did earlier.
Equipping his Cloth, Koga faces the Bronze Saint Hook whose element is earth. Charging straight at the Bronze Saint, Koga's attacks are easily defleceted and he is left at a disadvantage as Hook unleash his "Ground Needle". Koga nonetheless resumes his attacks as Hook attack and wounds him further each time, having studied Koga beforehand. However, as Souma emerge and encourage Koga to never give up, he once again prepares to fight.
Charging again, Koga succesfully evade Hook's "Ground Needle" this time, having studied Hook's attacks the hard way by allowing him to attack in order to realize the pattern. Finally getting close, Hook attempts to climb to the height in order to avoid Koga, but he simply runs up the rock and wounds Hook with the "Flash Fist", granting him victory at last. He is later shocked to see Eden's tremendous strength as he defeats Dali, a Saint of the wind element, in one hit.
Talking with Geki
As Koga trains for his upcoming battle in the Saint Fight, Koga is approached by Geki who tell him of Seiya's unbreakable determination which allowed him to stand up no matter what. Geki also mentions Seiya's signature technique "Pegasus Ryu Sei Ken", before leaving Koga to train.
After Yuna's victory against Guney, Koga face off against Souma in equal battle. Exchanging blows, Koga is shocked as Souma begins to use his element, retaliating with his own. The two Bronze Saints are quite equal in strength until Souma burns his Cosmo intense before unleashing a new technique, the "Lionet Burning Fire".
As Koga is hit with that technique, he faces certain defeat as Souma's Cosmo has become to strong, he is reminded by Geki's words about Seiya's determination. Remembering the name of the tecnhique he used the first time he got the Cloth, Koga once more stand up against Souma.
Unleashing his attack once again, Koga retaliates with his "Ryu Sei Ken" which succesfully deflects the "Lionet Burning Fire" and grants him victory as Souma is defeated.
After Eden's second victory against Paradise, Koga is taunted by the Orion who states that he, Koga, Yuna and Ryuho are the four remaining finalists. Swearing to defeat Eden soundly, Koga asks himself what's wrong with Eden who simply walks away before noticing a carriage.
Rushing to the location as he hears Athena has arrived, Koga is confronted by Martians whom he easily kills with his "Flash Fist" before entering the room where Athena is. However, he notice that the girl in front of him is not Athena before he is confronted by the headmaster of Pallaestra, Ionia. As he is scolded by the headmaster, he is shocked to hear that Ionia serves Mars before witnessing him equipping his Gold Cloth, revealing himself as a Gold Saint.
Attacking Ionia, Koga is easily defeated as Ionia use the "Domination Language" to restrain Koga's movements, before allowing the Darkness to consume him and spread out to the entire Pallaestra in the proccess.
In the prison, he meet a student who have been trapped for a while, who reveals himself as Haruto, who discovers a plan to escape. They successfully escape before facing the Beetle Brothers, killing one of them each with little effort. They later reunite with Souma, Ryuho and Yuna, who have managed to escape the massacre at Pallaestra before the five of them venture to save the girl Koga had met earlier.
When they reach the tower of Babel, Koga once more find the girl, who reveales herself as Aria, and they attempt to escape. However, the Gold Saint Micene witness them and pursue them.
Reaching their friends, Koga attempts to send the others ahead as he will distract Micene. However, only Aria and Yuna escape as Souma, Ryuho and Haruto remain behind to assist Koga. When Micene arrives, all four Bronze Saints burn their Cosmo and engage Micene one at a time, although they are all defeated.
With three of them defeated by the Gold Saint, Koga attempts to fight as well, but is interrupted as Mars arrives after sensing Koga's Cosmo. Before the god of war can eliminate Koga however, he is saved by Seiya's soul who engage Mars in a massive battle, before disappearing once again.
Disrupting the tower of Babel
Branding Koga and his friends traitors, Mars started sending Silver Saints under the command of his daughter Sonia. Koga arrived to save Yuna and Souma and helped Yuna defeat Johan before making a distraction for Miguel, allowing their escape. However, he pursued them, and the Bronze Saints were forced to fight him, being easily outmatched by the Silver Saint. However, Koga was saved by the arrival of Shun, the legendary Andromeda Bronze Saint who fought with Seiya and Shiryu. After Shun had wounded Miguel, Koga and Ryuho decided to put their lives on the line, risking everything in order to defeat Miguel. Ryuho first dealt a powerful Sho Ryu Ha to Miguel, before Koga finished the fight with his Ryu Sei Ken, shattering Miguel's Silver Cloth and defeated him by sending him down the ravine.
The Core of Wind
While travelling, the Bronze Saints encountered a huge whirlwind, and tries to go inside. When Koga gets in, he finds Fly who just defeated Yuna, and starts to fight, but is no match to the overweight Silver Saint. However, Koga refuses to stand down, and rises up again, while telling the Silver Saint that a true Saint defends Athena, not give in to own personal feelings just to get promoted to a Gold Saint, before he finally defeats Fly, and the Bronze Saints manage to disrupt the whirlwind, which is actually a Wind Core, one of the cores holding up the tower of Babel.
The Core of Earth
With that in mind, Koga and his friends decides to destroy all the Cores, and start by travelling to the Earth Core, while meeting Ichi on the way, but later have to fight him as he has betrayed them just to become a Silver Saint. Koga manages to defeat him after a hard battle, while Haruto destroys the Earth Core.
The Cloth Repairer
The Bronze Saints then travel to desert areas where they meet Raki, who is searching for Stardust Sand. They find the Sand, but Dorie arrives and the Bronze Saints are forced to fight. After a fierce battle, Koga is able to defeat Dorie and they travel onward to find another ruin and destroy it.
The Cores of Fire and Water
They head to the Fire Ruins, where Koga has to calm down a angered Souma, and after seeing him win the fight and destroy the Fire Core, they keep travelling to Rozan Goroho, where Shiryu lives with Shunrei and Ryuho, who has already started to search for the Water Core, but is ambushed by the Silver Saint Mirfak, whose ancestor was beaten by Shiryu 25 years ago. Koga, Yuna and Haruto arrives to help Ryuho, but they are turned to stone. After Ryuho defeats Mirfak, Koga and the others return to normal, and witness Ryuho destroying the Water Core, and they decide to travel to the last ruin: the Thunder Ruins.
The fighting spirit of the flightless Pegasus
However, more problems arrive before they get the chance of reaching the Thunder Ruins. Eden decides to take matters into his own hands, and attacks Yuna before finally having the long awaited battle between himself and Koga, where Koga is easily defeated, despite his best efforts to fight back. After failing to defend Aria from Eden, Koga falls into deep frustration and is lead by Yuna to a place where he could find himself again. When Koga goes inside, he suddenly falls, and he encounters a mysterious man who tricks the young Pegasus to fight, only to witness the man easily deflecting the Ryu Sei Ken, and he reveals to have a huge Cosmo, before launching a Diamond Dust at Koga, telling him to burn his Cosmo to the limit, or he wouldn't be able to break free. Koga manages to break free, and heads back to Yuna, as the man tells him to keep going, and that his friends are waiting for him. When Koga returns, he decides he is going to save Aria and not lose to Eden again. With that in mind, the Bronze Saints travel to the tower of Babel again and searches for Aria, but finds out she has traveled to the Thunder Ruins with Eden, in order to destroy the final Core.
The Core of Thunder
When the Bronze Saints arrive at the Ruins, the Bronze Saints fights of Silver Saints standing in their way, while Koga resumes his encounter with Eden, and manages to hold a little better this time, but is once more beaten. However, Koga submerges from the ground, hitting Eden for the first time, and keeps fighting him while Shaina destroys the Thunder Core. Eden is angered by this and proceeds to kill Koga, but before they can keep fighting, darkness covers Koga's eyes, and the Bronze Saints fall down the dark abyss, where they all confront their worst memory, with Koga hearing from a false Saori about his true Cosmo element: Darkness.
The Darkness ruins and death of a friend
Koga keeps burning his Darkness Cosmo, without control, but Aria appears, calming him down, and returns his Light Cosmo, and they destroy the final Core, turning it from Darkness to a Light Core, before Mars appears and the Bronze Saints do all they can to defend Aria and decides to fight Mars. Despite all their best efforts, they are no match for the God and Koga witness Aria being killed by Mars. After Mars leaves, the Bronze Saints mourn their friend's death, before being reluctantly teleported away, not wanting to leave Aria.
The New Zodiac Battle
After mourning the death of Aria, the Bronze Saints found themselves at a staircase ascending further up with a great light in the middle of the staircase. They decide to travel climb the stairs, until they arrive at a temple where they meet Kiki, who explains to them that Mars is using Aria's staff in order to draw the planet Mars to Earth and create new life by using the life energy of the Earth, and if the Bronze Saints wish to stop him, they will have to go through all twelve temples, each guarded by a Gold Saint with full mastery over the Cosmo and the 7th Sense. Kiki repairs Koga's Cloth, and Koga goes first while Kiki repars the remaining Cloths.
At the second temple, Koga faces Harbinger, and is easily defeated by the huge power of the Gold Saint, even though he did surprise Harbinger when he attacked with the Ryu Sei Ken, only to be hit by Harbinger's Great Horn. After the other Bronze Saints have tried fighting Harbinger and fallen, Koga has stood up again and once more challenges the Gold Saint, now with more confidence than before. After launching another Ryu Sei Ken against the Greatest Horn, Koga finds his friends have disappeared and is alone to fight Harbinger. Koga decides that in order to uphold his promise to Aria that he would save the world and stop Mars from destroying Earth, that he cannot fall yet, and so he stands up once more, to Harbinger's great shock. Once more, Koga attacks with his Cosmo burning and he manages to bring Harbinger down to his knees, who then acknowledges Koga's bravery and finally allows him to pass through.
He would later appear again to fight Paradox, only to fall for the hateful personality of the Gold Saint, and he later witnesses Ryuho attain his 7th sense and defeat Paradox.
When the two Bronze Saints arrive at the fourth temple, they fight against Schiller, and Koga drags the Gold Saint with him to the Meikai Ha where he for the second time loses control of his Darkness Cosmo and nearly kills Schiller because of the Darkness. However, Yuna manage to calm him down before taking care of the Gold Saint herself.
After the battle against Schiller, they keep running up towards Mars, and they arrive in the nick of time to save Haruto and Souma being killed by Fudo, but are easily defeated despite Ryuho and Yuna having attained their 7th sense. However, Eden arrives just in time to save them from being killed, and he sends them onward while he deals with Fudo on his own.
On their way to the seventh temple, the Bronze Saints are attacked by Tokisada, before being teleported to the seventh temple, where they see Genbu take over the fight untill Tokisada drags Haruto and Ryuho with him to the End of Time, while Koga, Souma and Yuna head onward to the eight temple where Souma stays behind to fight Sonia who is now the Scorpio Gold Saint.
As Koga and Yuna reach the tenth temple, they would encounter Ionia, praying before a statue of Athena. Questioning the Gold Saint why he has a statue of Athena in his temple when he was the one who offered her to Mars in order to create a new world, Koga angrily attacks Ionia, swearing to take him down in order to save the world from evil. However, Ionia once again overpowers Koga with his words, and make him and Yuna fight each other before making Koga succumb to his Darkness Cosmo. It fails, and Ionia decides to kill Koga by drawing forth his strength and stamina from his youth, almost killing the young Pegasus with his overflowing strength.
As Koga's headpiece shatters and he realizes that he will die, he suddenly feel the Cosmo of Aria and Athena, once more burning his Cosmo. Finally attaining his 7 sense, Koga finally defeats Ionia with the newly learnt Pegasus Sui Sei Ken which completely pulverize the Gold Saint.
Later, the Bronze Saints keep heading onward to the last temple where Koga once more surrendered to the Darkness Cosmo, but thanks to him having reached the 7th sense, was able to control it for a little while, before it almost took over him, but he was calmed down once again before he headed onward to fight Mars.
Pegasus and Orion vs Mars
Reaching the top, Koga attacked Mars, and was able to hold better this time, having awoken his 7th sense in battle against Ionia. However, the God swiftly dealt with the Pegasus and he was saved in the nick of time by Eden. Being told by Eden to move ahead and retrieve the staff of Aria, Koga left Mars and Eden and made haste for the staff. Struggling to get the staff, Mars arrives and mercilessly attacks Koga, until Eden once more arrives to help turn the tables. After a long, hard battle, with the help of Eden, Koga burned his Cosmo to the 7th sense, and defeated Mars with his Sui Sei Ken. However, time was up, and the planet Mars had started to draw energy from Earth. Koga and Eden were transported to Mars by Amor where they had the final encounter against him.
Abzu, the God of Darkness
After a failed attempt to awake Abzu which resided inside Koga, Koga suddenly fought back against the Gold Saint with a much larger power and was able to keep ut with his attacks. However, he finally saw Saori, and runned over to save her. However, the Darkness Cosmo kept burning in him, and with the darkness from Mars combined with his own, awakened the great God of Darkness, Abzu. Being Koga no more, Abzu proceeded to kill Saori, but the other Bronze Saints did all they could in order to defend Athena, but to no prevail as Abzu's Cosmo was even stronger than Mars', and the Bronze Saints were thus easily defeated, as well as dealt Darkness wounds. However, all hope was not over yet.
Possesed Pegasus vs. Legendary Pegasus
The Cosmo of Souma, Ryuho, Haruto, Yuna and Eden broke the Darkness chains that held Seiya captive, and once more, the former Pegasus Saint returned to fight against Abzu, although his efforts proved useless in the beginning, as the Darkness wounds he had proved as a handicap and he could not burn his Cosmo without hurting himself. But he would not give up bringing Koga back, and he fought alongside Yuna in order to save Koga, but they were once more deflected, before Seiya launched a final Ryu Sei Ken and Abzu used Koga's Ryu Sei Ken to retaliate, but Seiya proved victorius this time, expelling Abzu from Koga.
The final battle between Light and Darkness
With Abzu out of Koga's body, everything seemed to be over. However, Abzu still lived, and he took Athena, swearing to kill her no matter what. But Koga, now donning Seiya's Sagittarius Gold Cloth, pursued Abzu and fought with everything he had, only to be deflected and almost killed. But the Cosmo of all his friends enabled him a massive Cosmo in his right arm which helped him fight more equal against Abzu, before finally burning his Cosmo to the extreme limit, and destroyed Abzu.
A year after the defeat of Abzu, Koga decides to retire as a Saint, as his Cloth was shattered during the battle against Abzu. However, after Tarvos, a Pallasite serving Pallas arrives to kill him, Koga achieves a miracle, reviving his Cloth in a new form, returning to his duty as a Saint. During several confrontaions against Pallasites, his Cloth receives a scratch, which Genbu would later berate Koga for, saying he put to much confidence in his new Cloth to think about.
The battle of Pallasvelda
He later travels to Pallasvelda with his friends, meeting Seiya and enter. As Seiya draws the footsoldiers away, the Bronze Saints lead the Steel Saints onward, meeting Tarvos again. Koga tells the others to go ahead, while he settles the score between them. After nearly being killed, Ryuho appears to save Koga, and the two of them defeat him after a tough battle.
First encounter with Pallas and Titan
Koga encounters a young girl, taking her with him to save her from the Pallasites, reuniting with Ryuho, Souma, Yuna, Haruto, Subaru and Eden. The girl then reveals herself as Pallas, the one they have been looking for. Titan quickly arrives and stops the movement of the Bronze Saint and is about to kill Koga. However, Seiya arrives and confronts Titan and Pallas. Launching an arrow at Titan, the arrow is reflected, but Koga intervines, damaging his left shoulder on his Cloth.
The Cloth destroyer
Koga, Ryuho, Haruto and Subaru keep moving forward until they encounter Mira. Thinking he is an easy opponent as he has no armor, Koga rushes to attack, but is quickly defeated, and the Pallasite destroys the entire right shoulder of Koga's Cloth.
Pegasus and little brother
Still pushing forward, Koga, Ryuho, Haruto, Subaru and Eden encounter Celeris, the Equuleus Bronze Saint. After talking for a while, the Saints must fight Thebe and his Pallasites in order to defend the villagers. Koga later witness Subaru equipping the Equuleus Cloth, becoming a Bronze Saint as well.
Reparation of Cloths
With only Eden and Subaru capable of dealing with the Pallasites as their Cloths are too damaged to move on, Koga and his friends make haste to find Kiki and repair their Cloths. After having them fixed, they keep moving forward to fight.
After breaking through the Gate of Time, the Saints press forward until Europa meets them. Saying that only one of the paths lead to Pallas, the Saints split up into groups of four.
Heading through Alfheim, Koga, Yuna and Souma encounter Surtr who easily deflects their attacks until Shun arrives to fight alongside them. After a hard battle, Koga removes his Cloth to enter the Cosmo Barrier and destroy the Mystic Stone, allowing Shun to defeat the Class 2-Pallasite.
Moving onward, the Bronze Saints encounter Aegaeon and witness the power of one of the Heavenly Kings. Being no match for the Class 1-Pallasite, the Bronze Saints are easily defeated. However, Koga burns his Cosmo and manages to crack Aegaeon's sword further, before Ikki arrives to save them. After Ikki sacrifices himself, the Bronze Saints move onward, running endlessly, witnessing the Cosmo of Paradox and Integra colliding.
After Paradox and Integra combined their Cosmo to disrupt the infinite corridors the other groups were running in, Koga, Yuna, Souma and the other Saints (except Hyoga and Shun who went after Europa) arrived at the battlefield between the Gold Saints and Gallia, witnessing Paradox's death.
Telling Athena and the Gold Saints to move onward, Koga, Yuna, Souma, Ryuho, Haruto, Subaru and Eden face off against Gallia, using their most powerful techniques to take her down, with no success as Gallia is unharmed and easily knocks them down one by one. However, after Subaru's sudden awakening of his enormous Cosmo once again, Koga and the others combine their Cosmo and finally awakens to the legendary Omega. With their new powers, the Bronze Saints attack Gallia and damages her Chronotector little by little until Koga finally kills her with the final blow. As they discover their Cosmo reached Omega, they keep moving to take care of the remaining Class 1-Pallasites.
As the Bronze Saints arrive at the battlefield where Shiryu, Fudo and Kiki sacrificed themselves, they encounter Hyperion, who is still alive but without his sword as the three Gold Saints were able to destroy it. As the battle begins, Hyperion easily defeats them in spite of them drawing forth the Omega they used to defeat Gallia. However, Subaru stands up and attacks Hyperion, drawing upon his massive Cosmo once more, finally sending Hyperion falling. But he quickly deals with Subaru and steals his time, before turning his attention to the remaining Bronze Saints. Seeing Subaru sacrifice his own life for his friends, The other Bronze Saints desperately attack Hyperion, but end up having their Cloths totally destroyed. However, refusing to give up, they once more stand up and burn their Cosmo, horrifying Hyperion who in panick attacks them with his full might, with no effect as they keep burning their Cosmo. As Hyperion moves in to destroy Subaru, the Bronze Saints stand between, gathering their Cosmo into one and reaching the Macro Cosmo, finally awakening their true Omega Cosmo. As their Cloths cover them once more in a more powerful state than before, Hyperion desperately tries to annihilate them, but they prove to be too strong for him and they easily damage his Chronotector. As Hyperion tries to take them down in a suicidal attack, Eden destroys his Chronotector completely before Subaru, who managed to return, finally defeats Hyperion by sending him flying up where he explodes from the impact of his own suicide attack, granting the Bronze Saints victory.
Koga has learned a few techniques during his adventures.
Pegasus Senko Ken: Koga burns his Cosmo and raises his right arm, gathering a huge ball of light which he attacks his enemy with, blinding them and taking them with surprise. He discovered this attack on his own while fighting against Ryuho.
Pegasus Ryu Sei Ken: The legendary move of Pegasus Seiya. Koga launch a great number of blue meteors which emerge at a great speed, and they increase in speed and power along with Koga's Cosmo. Koga used it for the first time after he equipped the Cloth, and has surprised many of his opponents by using that technique.
Pegasus Sui Sei Ken: Another legendary technique used by Seiya first. Koga burns his Cosmo and launch one huge comet of light. Koga first learned and used this technique while fighting Ionia for the second time at the House of Capricorn, where he completely shattered the Gold Saint and his Cloth.
Pegasus Rolling Crush: Koga first use this technique in Season 2. Just like Seiya, Koga grabs his opponent from behind, sending them both flying in the air, dealing massive damage his opponent as they land head first to the ground. Due to the impact, Koga is likely to risk damage at himself with this attack.
- Koga is the second Bronze Saint to host a god that is the true antagonist of a season, the first being Shun who was possesed by Hades ever since he was an infant. Koga had most of the darkness inside him as an infant, but Amor transferred the rest of the Darkness Cosmo from Mars to Koga, finally awakening the god of darkness Abzu.
- In spite of being a Saint with the Light Cosmo, his true Cosmo element is in fact Darkness, as he received it when he was an infant. However, Saori raised Koga and gave him the Cosmo of Light.
- According to Koga, when Abzu possessed him, he could feel it when his friends were injured while trying to defend Athena.
- When Seiya face Abzu in battle, it is revealed in a flashback that Seiya show an infant Koga his constellation, indicating that Seiya knew Koga would become the future Pegasus Saint.
- Koga is the last Bronze Saint to reach his 7th sense.
- Koga is 13 years old in the first season, the same age Seiya was when he received the Pegasus Cloth.
- In second opening of Saint Seiya Omega, Koga is seen fighting Micene as it probably was an idea to have them fight each other, as a little reference to Seiya and Aioria's battle from the classic series.
- Both Seiya and Koga have fought against the Taurus Gold Saint:
- Seiya fought against Aldebaran and Koga fought against Harbinger.
- While Seiya remained 13 during the original series through all seasons, Koga is 13 when he fights Mars and by the time they join the battle against Pallas, Koga is 14 years old.