Kiyoshi Miyafuji
First appearance: Chapter 56; Season 2, Episode 2 He is a very sceptical person, so he ignored the buddah monk's theory of Gantz room being a testing place of soul transfer to heaven/hell. Instead he been asking several questions to Katou about how this survival game works. He merged together with one of the aliens fighting Gantz team as a result.
Pictures
Mangaography