Haruka Takayama and Yuu Sonoda are best friends who are just starting high school together. However, as the school year begins and the two make new friends, Haruka worries that her friendship with Yuu will stop being special. After Yuu suggests that the two of them do something that is unique to them, Haruka suggests they kiss each other in secret as proof of their special friendship. Later, Haruka and Yuu get locked inside an empty classroom whilst kissing on the veranda, requiring them to cross a large gap between verandas to get to the neighbouring classroom.