Seongjeokpari Sonyeon

Heo Jae-Hyuk, who barely managed to return to school after enlisting to evade punishment for messing with a taken man. This semester, he tries to get his act together and focus on his studies, but old habits die hard—he finds himself on the brink of expulsion. However, Jae-Hyuk uses his quick wit to approach Professor Seong-Ho, who has unsavory rumors circulating within the department, and proposes a deal....!

(Source: Lezhin, translated)

Note: The fourth and final story in Lezhin's Jungnyeon Danpyeonseon (중년 단편선) Collection.