Sada, Kiyoshi

Kenji's classmate who wasn't part of the original gang. As a child, he often wears a mask, but was bullied a lot in school and eventually left after a semester, thus his face remains unknown to most of the gang.

[Spoiler] However, Fukubei meets with him and Sadakiyo asks if he can be his friend. He later joins the Friends and is the caretaker of Friend's replica childhood home. He becomes the English teacher of Kyoko Koizumi and takes her to the Friend's home, where he begins to realize that maybe he wasn't doing the right thing after all, and ends up burning the home, and taking Kyoko to meet his old teacher at the senior center. He supposedly dies in a fiery car crash while Kyoko and the gang escape, but appears in 3FE with his mask on as he tries to hold off Friend. [/Spoiler]