Iaian is the A-Class rank 2 hero of the Hero Association and a disciple of the S-Class hero Atomic Samurai. He wears Western armor and specializes in Iaido. His left arm was blown off by an alien, and he has been a one-armed man ever since. He and the other two students of Atomic Samurai, Okamaitachi and Bushidrill, are all immensely powerful swordsmen. The three of them together can even defeat stronger Demon-level threats. Still, they cannot advance to S-Class because Sweet Mask.