Nonaka, Katsuma

野中勝馬

He was an upperclassman during Hayami's time at the International Naval Academy, and they served together on the Grampus Development Team. In an effort to uncover Zorndyke's true intentions, he defied orders and traveled to the South Pole, where he encountered the Zorndyke Fleet. After allowing Hayami to escape, he vanished without a trace.
Years later, he reappears as the only man known to have escaped from Zorndyke, though not without cost. Now a hybrid of human and aquatic mutant, he exists in a precarious state between his humanity and becoming one of Zorndyke's creations. Despite his condition, he still serves as a kind of living map, which No. 6 intends to use to bypass Zorndyke's fortress. Until that time, he is kept alive inside a metal capsule filled with water.