Gozen 0-ji no Ookami Koushi

From Fujoshi Bitches:

Suwa is the student whose love is unrequited for his teacher- Kannagi-Sensei. Kannagi-sensei is handsome and gentle, with a voice that instantly arouses Suwa. Contrary to appearances, the teacher who looks like he has everything all together is actually an untidy person with no fashion sense, so Suwa must come to his classroom to take care of him. However, since Suwa has passed his class with flying colors, this relationship will soon be over. But on the last day of school, Kannagi-Sensei suddenly says “I thought you loved me?” and forcibly kisses Sawa!? The dual-natured sadistic college professor and the student he’s toying with- their thrilling love story<3