Sensei wa Sonna Koto Oshietenai!

Masaki Tsuji is a divorced high school teacher in his early 30s. Lately, he's been running into a groper on his train ride to work. At first, he thought it was a mistake, but once the hand reaches around the front, things start to escalate! Then a voice whispers, "You're cute, Mr. Tsuji." He can't stop thinking about the perpetrator all the way to school. When Souta, a student who usually gets good grades, hands in a blank test sheet, Masaki calls him in for a talk. They meet after school, and once Souta confirms that they're alone, he goes in for a kiss! Souta whispers to a panicking Masaki out of the corner of his mouth, "Have you been getting groped on the train recently?" Souta ties him up and starts playing with his body...! This is a secret school love story between a handsome student and his 30-something teacher! (Source: Renta!, edited)