Sakuma has short dark-coloured hair and also dark-coloured eyes. He wears the school standard male uniform.
He was described by Tachibana as an unpopular boy with mature feels. He couldn't resist as the non-existent student because of the pressure and rejection.
He appeared in Tachibana's flashback from the chapter 11 of the manga. When she was at school, suddenly she heard Sakuma saying "I do exist, I'm right here, I exist". After semester 2, because of the pressure and rejection, he broke the agreement. When the new year started, he committed suicide.
- His surname, Sakuma, may come from a profession, such as the name "Fisher" which was given to fishermen.
- He is mentioned in the anime.