Signal Heart

One day, the protagonist's house is suddenly destroyed by a fire. Since he has nowhere to live, he moves to a school dormitory. But a dormitory for male students is full, so he is forced to live at a dormitory for female students as a caretaker. Days later, the school decides to pull down the male dormitory and construct a new one since the old one is in pretty bad shape, especially compared to the female dorm, which also has more room but less students using it. However the new dormitory will only be ready after everyone has graduated, which leads to an uproar among the male dorm members. The school chairman then ask both male and female dorm to have a battle at the upcoming school festival. The one who earns more sales is the winner, if the males win they get to exchange dorms with the females. Because he lives in the female dormitory, our protagonist gets involved in this battle on the girls side...

[Edited from ErogeShop]