Katei Kyoushi no Yuuwaku Sex "Gomu... Nakunaru made Tsukaou ne"

"You can do whatever you like." Yuki, a student who fails the university exam once, has his tutor watch over his studies, but he's concerned about her beautiful face and big boobs, so he can't concentrate on his studies. The teacher notices and gives him a condition, "If you get good grades in the next mock exam, you can do whatever you want." Yuki doubts her words, but the result of his mock exam is good. The teacher says, "I have to give you a reward," and reveals her plump breasts. Yuki, who has been holding back, can't stand it anymore, so he starts to touch her...
(Source: Eromangajima, translated)
Note: Released in 18 episodes and sold as 6 chapters.