Coy and self-conscious high school student Karin Karino never paid much attention to boys until she met Kiriya, a popular student from a nearby boys' school. Karin and Kiriya embark on a romantic journey despite Karin's classmate Yuka's best efforts to sabotage their relationship, but Karin soon learns that living happily ever after isn't on the curriculum when she becomes Kiriya's centre of attention, as well as embittered Yuka's bull's-eye on her dartboard of hate. Karin and her friends begin preparations for their trip to Okinawa, and Kiriya's past slowly unravels after his father forbids him to go on the trip. Karin and Kiriya's relationship blossoms, but intimacy rises to the surface of their turbulent sea of young love as the pressure to give in torments romance newbie Karin.