Natsukage ni, Sayonara

The summer before starting college, Fuuka decides to work part-time at a beach house. There he meets Jun, the youngest son of the owners. Jun is always crying or laughing and is so full of emotion that it causes nothing but trouble. Still, Fuuka finds it impossible to tear himself away from this boy, two years his junior and yet closer to his heart than anyone else has ever been. But even the longest summer has to end sooner or later.

(Source: Takeshobo, translated)