Kao dake yoi Classmate ga, Yatara to Guigui Kuru Yuri no Hanashi.

Ritsu Kaidō, a member of the top social caste at school, had a boyfriend—not out of love, but because it was what everyone expected. As their one-year anniversary approached, the moment finally came for their first kiss… But just then, Tsuzuru Yarai, a quiet classmate, happened to witness it all—!?