住在天空与海洋辉映的城镇“藤泽”的梓川咲太，就读高中二年级。 　　他与既是学姐又是恋人的樱岛麻衣所度过的令人雀跃的日常，随着初恋对象牧之原翔子的出现而改变。 　　不知为何，存在着“中学生”和“大人”两个翔子。 　　出于无奈开始和翔子住在一起的咲太，受到“大人翔子”的捉弄，和麻衣的关系也变得尴尬。 　　此时，“中学生翔子”身患重病的事实被发现，咲太的伤痕开始隐隐作痛——。In Fujisawa, where the skies are bright and the seas glisten, Sakuta Azusagawa is in his second year of high school. His blissful days with his girlfriend and upperclassman, Mai Sakurajima, are interrupted with the appearance of his first crush, Shoko Makinohara. For reasons unknown, he encounters two Shoko's: one in middle school and another who has become an adult. As Sakuta finds himself helplessly living with the Shoko's, the adult Shoko leads him around by the nose, causing a huge rift in his relationship with Mai. In the midst of all of this, he discovers that the middle school Shoko is suffering from a grave illness and his scar begins to throb.