Isaac is the Kraken Marina General and one of the 7 Marina Generals guarding the Mammoth Pillars in Poseidon's realm. Once a sparring partner of Hyoga left to die after an accident, Isaac is saved by the mighty Kraken and later swearing allegiance to Poseidon, becoming a loyal General willing to kill any of Athena's Saints, even if he has to kill his friends in the process.
Isaac has green hair and eyebrows, and dark green eyes. However, after an accident where Isaac's left eye was stabbed by a shard of ice, he is left with a large scar across his left eye.
Isaac has during his training learned to cast all emotions aside as Camus have been trying to teach Hyoga as well, although at a different level. Ever since becoming a Marina General, Isaac reveals a rather cruel and emotionless personality, even hurting young children like Kiki during the battle between Athena's Saints and Poseidon's Marina Generals.
Arctic Mammoth Pillar
By the time Kaasa and the Antarctic Mammoth Pillar have fallen, Isaac confronts Hyoga who has recently arrived at the Arctic Mammoth Pillar with a powerful Cosmo. Once standing before the Bronze Saint, Isaac removes his mask and reveals himself to a shocked Hyoga who recognizes his former sparring partner.
Approaching Hyoga with a gentle voice, he suddenly kicks the Bronze Saint as he shouts out his name, revealing his new status as one of Poseidon's Marina Generals and guardian of the Mammoth Pillar. When Hyoga asks him about the day he lost his left eye, Isaac reveals that although he was supposed to die at that moment, the legendary Kraken saved his life and brought him to Poseidon's realm, where he was given the chance of becoming a Marina General serving him.
Attacking Hyoga once more with his rageful fist, he is shocked when Hyoga offers his own left eye rather than retaliate against his former comrade. Accepting the offer, Isaac leaps at Hyoga and pierce his left eyelid, wounding the Cygnus. Unleashing his "Aurora Borealis", Isaac effortlessly knocks out the Bronze Saint before realizing that Hyoga was willing to die to attone for his sins. Just then Kiki arrives with the Libra Gold Cloth, only to see Hyoga defeated and Isaac standing triumphant over him.
Demanding that Kiki hand over the Gold Cloth in order to destroy it, Isaac grabs the Appendix and grievously wound him by stomping on his back until he is suddenly interrupted by Hyoga, who has survived the "Aurora Borealis". When he hears that Hyoga is going to give his all this time to defeat Isaac, the General gladly accepts the challenge but finds himself overpowered with little effort.
Noticing Hyoga's Cloth turning Golden, Isaac learns of how the Gold Saints revived the Bronze Cloths with their blood, before Hyoga neutralizes the "Aurora Borealis".
Asking how Hyoga managed to become so strong, Isaac is further surprised as Hyoga takes a stance he has heard of before, the legendary attack of Camus. Refusing to be defeated, Isaac unleash his "Aurora Borealis", but Hyoga counters and overpowers the General with the "Aurora Execution", damaging his Scale in the process.
In his last dying moments, Isaac reveals the true mastermind behind Poseidon's revival and current battle against Athena, before he draws his last breath.