I suppose Koakuma could just be practicing the survival float; people in the Twitter thread keep asking the artist if Koakuma is drowning and he seems to be kind of ambiguous about it.
Way back when I was in college, some people from my dorm were trying to use an inflatable chair (that was intended to be floor furniture instead of a pool float) in a pool, and it was not balanced correctly for someone to actually float on it. The only person who could sit in it on water without flipping it over was someone who was extremely light. So a floaty chair has to be designed correctly so it stays upright when someone sits in it.
Patchy looks nice with the swimsuit and the different hair!