Inamori
First appearance in manga: Chapter 1
First appearance in anime: Season 1, Episode 1
Inamori's a blond guy in his early twenties who materialized in the Gantz room right before things got weird with the Onion Alien mission. He made an immediate impression by being difficult—when Yamada Masashi tried to get everyone to share the usual stuff (names, ages, how they died, what they were doing before all this), Inamori basically refused and just kept asking for cigarettes instead.
Kurono picked up on something too: he thought Inamori had pretty delicate facial features, kind of feminine looking. Beyond that, Inamori kept his cards close to his chest about who he actually was, which only added to the mystery surrounding him when everything started going down.
Content compiled by AnimeList.moe from publicly available sources.