Kaneki in black and white in Tokyo Ghoul represents his fragmented identity and mental state, with his hair color shifting between black (human/normal) and white (ghoul/traumatized), culminating in the iconic half-black, half-white look during his "Haise Sasaki" phase and the darker, fully black "Black Reaper" form, symbolizing his struggle to integrate his human and ghoul selves after extreme torture and trauma.