Haruka Takayama and Yuu Sonoda are two best friends who are just starting high school together. However, as the school year starts and the two starting making 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 start kissing each other in secret as proof of their special friendship. Later, Haruka and Yuu get locked inside an empty classroom whilst they were kissing on the veranda, requiring them to cross a large gap between verandas to get to the neighbouring classroom.

The graduation party for Mitsuki and Rina gets underway, with everyone giving them presents. During the party, as Yuu gets into an argument with Mitsuki over her kissing relationship with Haruka, Mitsuki, upon hearing that their kissing is part of a 'special friendship', confesses her love to Haruka. Following the graduation ceremony, Haruka is called about Mitsuki, who discovers Haruka knows nothing about love or dating and misinterpreted Mitsuki's confession. Haruka ends up rejecting Mitsuki, who leaves her with just a kiss on the forehead. Yuu, who had been watching them, bring Haruka to the old classroom, where they kiss whilst telling each other they love each other. With their feelings stronger than ever, Haruka and Yuu begin their second year of school.