Early summer, Maebara Keiichi had just moved to a remote mountain village. As he becomes close friends with a group of girls, he was enjoying his life in the village. However, when he starts to become suspicious that Ryūgū Rena, Sonozaki Mion and the others that Keiichi trusted may be deeply involved in successive murders that occur every summer, the situation around Keiichi gradually starts to turn. As if the girls' characters had completely changed, a sewing needle is found in his food, he is chased by mysterious men, and is involved in an accident that could have killed him. He could no longer trust anyone, and then one mystery leads to another, bringing out a shockingly bloody ending.

Mysterious transfer student appears. Lily disobeys the student council's orders and goes her own way. Hina, Rose, and Sumire were inspired by her appearance. "With Lily, we might be able to really change the school," he says, forming the Hanagumi. However, the strongest men in history stand in front of Hanagumi. This is the story of a small world revolution that can be found everywhere. However, a revolution in a small world may one day lead to big changes in the world.