Kimi ga Bokura wo Akuma to Yonda Koro

Yusuke Saito is a normal high school kid...well, normal enough, except that he can't remember anything from his life except the last six months. But when he starts to get confronted by people who insist they're from his past, who allege that he did horrible things to them...suddenly Yusuke's missing memories become crucial to remember. Otherwise, the skeletons in his closet may just make him a skeleton, too...

(Source: Kodansha USA)