After a longtime gaslighting by a sex partner, Yeonsu thinks of himself as a masochist. Yeonsu, an elementary school swimming instructor, starts teaching Cha Juhwan, a top star who secretly needs to learn how to swim for filming. To Yeonsu, who believed life was over and there was nothing to see at 29 years old, the world makes a 180º change as Cha Juhwan approaches. "I like to be hit, and my partner likes to make me this way" "Then do it with me too" "Not a painful, but a normal relationship. Let's do it"