Kosuke Mizushima is a high school student at a provincial city and enjoys a comfortable life. One day, due to Kosuke Mizushima's excessive joke, his class is interrupted. The teacher gets upset and makes model student Mai Hayase keep an eye on Kosuke Mizushima. Kosuke Mizushima and his 4 friends all had crushes on Mai when they were in middle school. Due to a small incident, Kosuke Mizushima and Mai Hayase get close.