Young Bad Education

From Bunny's Scanlations and Must Be Endless:

Top student Mizusawa, third year in high school, was kissed by his drunk homeroom teacher, Takatsu (37 years old). After being told by a dazed Takatsu, that he'll stop the unrequited love he's been holding for him ever since his school entrance, Mizusawa has for the first time taken an interest in him. A few days later, ever since his secret was known, Takatsu has been scared of Mizusawa getting close to him and each time Mizusawa would shudder with excitement. However, one day after learning that Takatsu has gone to a marriage interview, suddenly Mizusawa realized that he wants the older man. Also features the adult love between a mail carrier doggy type and an ill-tempered novelist.

Volume 1 : Young Bad Education
Volume 2 : Young Good Boyfriend