In the third semester of high school, Sakuta Azusagawa attends his girlfriend Mai Sakurajima's graduation ceremony. As he waits for her, a young girl who resembles Mai from her childhood appears, sparking questions of reality. Sakuta receives a call from his father about his hospitalized mother, leading him to meet her with his sister Kaede. Anxiety and an unknown scar on Sakuta's body foreshadow a potential new adolescent syndrome.

Faced with the truth about Miori and Touko Kirishima, Sakuta must make a choice. This will be his final case of Adolescence Syndrome!

After a draining December, Sakuta is quickly nearing the end of his second year of high school. Since Mai is a third-year student, they don't have much time left together before graduation rolls around. Meanwhile, his sister, Kaede, is slowly but steadily venturing outdoors again. Just as she begins to find her footing, she announces her most ambitious goal yet—attending her brother's high school! Sakuta knows better than anyone how difficult this will be for Kaede, and he's ready to support her however he can. He's just not sure if that's what's best for her...or what she really wants...

Rascal Does Not Dream of a Dreaming Girl is a movie that follows Sakuta Azusagawa as he tries to help his girlfriend, Mai Sakurajima, who is experiencing strange phenomena. As Sakuta delves deeper into the mystery, he uncovers a tragic story of love, loss, and the power of friendship.