Hatsukoi wa natsukanai

Satoru returns home to find his live-in girlfriend cheating on him with a stranger. His feelings for her suddenly cool and he leaves without even getting angry.
Then for some reason, the other guy, Manato, chases after him!?
Satoru has nowhere to go, so he goes for a drink with Manato and they end up spending the night together in a drunken stupor...