I feel kinda bad for people who are actually in bdsm (not me, but I have a lot of friends who are dommes or subs) since this is bad portrayal of it and people outside of it just think that this is what bdsm is about when it's not.
Remember! Consent is key no matter what happens, whether that be breath play or knife play, remember that both parties need to consent to it! lmao
That being said, if you keep that in mind, it's just a manga on one person beating a person up, and the other wanting it lol so whatever floats their boat xD