Saiteihen no Otoko

Masahiko Murai is a loser, but at least he isn't the biggest loser in his class. That "honor" belongs to Yamada, a smelly, disgusting individual who suddenly winds up with a girlfriend, meaning that Masahiko is now the class' resident failure. In order to save himself from further disgrace, he decides to lie and tell everyone that he is in a long-distance relationship with a girl named Haruka Mizusawa, his childhood friend.

However, Masahiko gets the shock of his life when Haruka transfers into his class the next day. She proudly declares that she is dating Masahiko, and everything seems to be going his way. There's just one catch: known only to Masahiko, Haruka died five years ago. So who or what is his new girlfriend?