Wataru is part of the Adult Tomodachi Games. He appears in the first game, "Prison Game of Friendship", as "Prisoner Number 0011".
He is a very nonsociable and quiet individual, the only one having stayed alone during the before party.
During his time as a mart employee, he was seemingly used as a scapegoat for performance more than once. Their reasoning for this was because unlike himself, the others are "proper" human beings. He was blamed for failing to match the proceeds.