Based on the erotic game by Tanuki Soft.

Sae Inagaki looks cool and her attitude is even cooler. She’s that honors student that is good at school and sports. But due to her shyness, she can’t communicate well and often spends time alone in the classroom. Her homeroom teacher, Youichi Shiraishi, gives her some attention seeing her alone all the time. Sai falls in love with him because of this. One day, she confesses to him and boldly puts her lips to his. Willing to do anything for him, she does every single thing that he wishes of her.

The second episode features Youichi in a different setting of Shoujo Kyouiku RE.
Sex with my sister all day and all night! Nana watched a horror movie and can’t sleep by herself today, so she has Youichi sleep with her. Nana was expecting Youichi to tease and play with her body a little. But instead he is fast asleep. Pissed, she starts playing with his body instead.