Ah yes, the usual caught masturbating routine. It could have easily gone the 'masturbate over body' or 'take advantage of her when asleep' route, but this of course works out just nicely too.
Great ending though! Much respect to the guy, he's already thinking about what he has to do to properly take responsibility, as a good Hentai Protagonist should.
Really, I'd ask for this to have a Vanilla tag, would fit perfectly with the Tsundere goodness on display here, definitely.
Evidence.