Natsuyasumi Sousaku Nikki

Presented as a diary, this story chronicles Senku Ishigami's summer vacation filled with sexual encounters with a faceless mob character across various locations, including his room, a library, a club room, a summer festival, a love hotel, and the beach. Following a period of abstinence while Senku helps Taiju finish his summer homework, the two reunite for intense sexual intercourse. They spend the final day of their summer vacation eating watermelon together. Ultimately, Taiju reflects on these events, revealing that the entire diary was actually a detailed plan for the summer of 2019 that never came to pass.