Mutually Beneficial summary:

The Republic of Korea, where humans and beastmen, beings of opposite poles, coexist. 'Tae-seong', a shark, has to win the prize money in a swimming competition to pay off his loan debt, but his rival 'Yun-jae' wins the first prize each time. Then one day, Tae-seong finds out that Yoon-jae is actually a 'human' in the shower room, and tries to threaten him to pay back the debt on the condition that he will keep Yoon-jae secret, but somehow it doesn't work out."When I call, come and suck my bottom and fuck me"