I think it's like, a 50/50 split regarding who tops, and Mafuyu tends to be Really Vanilla About It, whereas Kanade does not

When Mafuyu tops, it usually starts with him being the one to initiate, which means Bothering Kanade While She's In The Middle Of Something (she enjoys it). Rarely does he ask for sex in a situation where it'd be expected; in bed, or while cuddling, or what-have-you. It tends to be fairly surprising, during the most mundane activities. Kanade reaches into the cupboard in the morning to grab a mug, and suddenly he's behind her, snaking his arms up her sides to grab her chest... Or she'll be in the middle of working, and he'll walk into her room and stare at her menacingly, having decided she's gone too long without a break and needs to be eaten out Right Now.

Things tend to get markedly weirder than "Mafuyu straps Kanade within an inch of her life and then fucks off to go do something else" when Kanade is the one topping. She will just do Anything to that guy. Maybe she'll tie him up for hours with a vibrator on every erogenous zone imaginable. Maybe she'll make him masturbate with a shock collar on, and activate it every time he moans. Maybe she'll have him listen to a hypno track she made just for him... the possibilities are endless, because Kanade is absolutely into every kink to ever exist