Matz lovers! I have uploaded my new seongjoong fanfic on ao3. Title: Swimars.
Here's a summary: Hongjoong wants to learn how to swim, so he signs up for adult swimming classes. His swimming instructor, Seonghwa, turns out to be hottest man he’s ever laid eyes on, and he soon finds himself developing a crush on him. What happens when Seonghwa offers him a private swimming lesson?