Sakuta attends Mai's graduation and meets a child who looks like Mai. He gets a call about his mom, sees a scar, and wonders about a new syndrome.

It's March, and there's only one month left in the third semester. Sakuta Azusagawa attended the graduation ceremony of his girlfriend Mai Sakurajima. As he waits for Mai on the shore of Shichirigahama, an elementary school student who looks just like Mai from her childhood days appears in front of him. "Uncle, who is it?" Is this a dream or a vision?Sakuta is reminiscing about his mysterious experience when he receives a phone call from his father. "It's about my mother. She said she wanted to meet Kaede". It was a wish to "see her" from Kaede's mother, who had been hospitalized for a long time because she could not fully accept what had happened to her. In response to his mother's wishes, he decides to meet her mother with Kaede, but he cannot hide his nervousness at the opportunity to meet her for the first time in a while. An unfamiliar scar appears on Sakuta's body. Is this a harbinger of a new adolescent syndrome?