Boku ga Yarichin ni Natta Wake

Kōta is a student at a prestigious academic high school, but he finds his daily life boring. The only highlight is the presence of attractive girls in his class, though he and his unpopular friends have no luck with them. Unbeknownst to his classmates, Kōta has a secret: Hiyori Mizukawa, a girl popular with the boys, is his childhood friend.

One day, Kōta ends up studying for tests with Hiyori at his house. Alone together in the empty house, he tries to convince himself nothing will happen, but he can't help feeling hopeful. Suddenly, Hiyori leans in close and whispers, "What about me...?" When she says, "Do whatever you like..." Kōta finds himself taking her virginity, setting off a chain of events that will change their relationship forever.