It's mostly purely sexual. It's so that he can raise his hips more to a certain height. Sorry for ruining it.
Well it's comfortable both ways. XD
Yeah but it is still quite considerate of him, whit that position Mizushawa has to raise his hips either way, with a pillow it's much easier on him.
Yeah thts mostly for comfort cause it can be done without a pilow. Even tho it feels Supeeer amazing, deff better with a pillow
I love that Aoki always puts a pillow under Mizasawa's back whenever they're doing it. It's a small thing, but adorable!!!!