Dolphin Yojeong
Mok-Hwa is an unemployed young man who wants to commit suicide, but instead he finds himself signing up for swimming lessons. He eventually begins falling for his swim teacher, a beautiful man with a great body. But as they become closer, Mok-Hwa can't help feeling something's a little strange...
(Source: Lezhin US, edited)
Note: Lezhin Comics was the publisher until March 12, 2018. The series moved to Ridibooks on July 31, 2019. Chapter count includes a prologue and 20 extra chapters.