After his parents' divorce, Koyomi Takasaki, who lives with his mother, enters a local high school: He attempts to make friends in his new school, but his social awkwardness combined with an atmosphere of focusing on studies means he is unsuccessful: But one day, he is suddenly approached by his classmate Kazune Takigawa: She says that she has moved from the 85th world and that Koyomi and Kazune are lovers there: Who is Koyomi Is Koyomi in the parallel world himself in this world