Based on the adult manga by Akazawa Red.

Summer will end and will enter the second semester. However, the summer schoolwork has not been held yet by Mei, Yama, and Ayumi. All this because during the summer, Yama and Mei just play games and sex every day, so the summer schoolwork that he wants to do not even work.

(Source: Nekopoi and Has Been Translated and Edited)