(GANTZ AU)

Kato (18) is a tall handsome young man with broad shoulders and toned physique. He has shoulder-length black hair back and very dark almost black eyes. He wears clothes in a stripped-down style.

Kato and his brother were orphaned when both their parents died, forcing them to live with relatives. Kato and his brother were mistreated by their relatives, and Kato dreamt of finding an apartment of his own, where he and his younger brother could live together in peace. Before his death, Kato's father was a fireman, which helped inspire Kato's own willingness to risk his life for others.

Kato is a high school student and childhood friend of Kei Kurono who become a member of the Tokyo Gantz Team after both of them suffered a fatal train accident.

After seeing a homeless man fall on the subway track, Kato goes down to help him. However, the man is too heavy to be carried to the platform alone. Spotting his childhood friend Kei Kurono, he calls to him for help, and the reluctant Kurono obliges. Horrifically, after getting the man on the platform, the subway train arrives and rips them apart, killing them. Instead of dying, they found themselves in a strange room along with six other people and a dog who have all recently died. Suddenly, a naked woman appeared on top of Kurono after committing suicide in a bathtub. There is a mysterious Black Sphere in the room that started to playing an old exercise song and told them to hunt a little alien. The ball opened up, displaying weapons and suits. Still in disbelief over the situation, Kato does not take his suit or any weapons with him then they were transported out of the room, after hunting the alien and being returned to the room with his friend Kato went home.

The next time he was sent to the room you appeared in there too.