I think Mahiro's wet himself like... 4 or 5 times in the main manga so far? The first time was the obligatory "guy transformed into a girl overestimates his ability to hold it in and wets themself just outside the bathroom" gag, every other time it's been like... "the author saw a plausible reason to have Mahiro piss himself, and took it". The main manga doesn't like, hard focus on it. It's just happened enough times that it's pretty clear the Author's got a thing for it and is just using it for a repeated gag.
