Rei Tsukumo is the main protagonist of the Kara no Kioku manga. Rei is quite mature and calm majority of the time, with a habit of slipping into deep monologues where he is normally a bit more anxious than what he shows and also when dealing with Zingai. Rei seems to be a bit reserved, having little interaction at high school with small conversations here and there. However, he does show kindness, as shown when Rei picks up a drawing a classmate drops and compliments him on the piece.

Spoiler

He apparently went to Tokyo due to family reasons, being that his parents' job. But it appears he met Yuu before moving to Tokyo, and there was an accident that killed his parents.