Ch 1) Two classmates Daiki and Kuni have their "first time" together. But afterwards things get awkward between them and Daiki starts avoiding his friend. Then Kuni introduces Daiki to his new girlfriend.
Ch 2-3) Takahiko can't stand Aizawa, a student in another class. As for the reason why, it seems that Aizawa has his eye on Takehiro, a mutual friend. To save Takehiro from Aizawa's evil clutches, Takahiko plans an onsen trip so he can reveal Aizawa's true colors. However, when he hears about this idiotic plan, Takahiko's best friend Magi is nice enough to play along, but...
The result is something Takahiko never anticipated!
Bokura No Mitsudomoe Sensou