Shishunki no Obenkyou

This is an anime adaptation of Meganei’s manga.

Kasuga and Kobayashi are two classmates but also childhood friends. However, Kasuga is curious and wants to know what a penis looks like, which torments his thoughts. One day, Koyabashi boasts to Kasuga for having better results on his exams. Seeing an opportunity to satisfy his curiosity, Kasuga offers a bet to his friend. The person getting the worst results in the next review will do whatever the winner asks of him.