Blackbutterfly

I read this manga a long time ago and it’s an ecchi manga with the ML being afraid of water. He goes to a swimming class to help ease his problem and he meet his childhood friend who is an instructor there. There’s some side characters as well but I remember the ML is afraid of water because of him almost drowning on a trip.

any slice of life with plot similar to sewayaki kitsune no senko-san or diary of our days at the breakwater??