Ajisai no Chiru Koro ni

A guy was dating his girl, but they both went to study at different academies. Before their last meeting, the girl promised that she will wait for her boyfriend when he finishes his studies at the academy and comes to see her. But during his absence, the girl was forced to have sex by the blond boy who charmed her. Thus the guy lost his future with his beloved ex-girlfriend without even realizing it.