I learned it as a combination of three things:
Bondage and Discipline
Dominance and Submission
Sadism and Masochism
BD
DS
SM
Only all squeezed together (painfully, one hopes) to form a single abbreviation.
As a warm, cuddly sadist, I enjoyed the hell out of this manga. I started reading it and thought it was going to be a pure gag manga, much like the relationship between Mayami and Reina in Yandere Kanojo.
But then something happened there in the middle chapters and the characters got some actual development and then it surprisingly turned into a touching story about love and getting in touch with your inner sadist (which is a topic with which I have some experience).
Hearkening back to the discussion about the nature of BDSM from three pages and two years ago, I personally don't enjoy BDSM without sex. My relationship to BDSM without sex is roughly the same as my relationship to non-alcoholic beer or decaffeinated coffee.
That's just me, though. I am fully aware that there are many BDSM practicioners who do it in a completely non-sexual way. Way back in the day, I used to go to the Black Rose Society meetings in DC. One of the folks who started it was a guy named Jack. Jack was like this cheerful little dude who looked like a fire hydrant and acted like a leprechaun. And he was totally into non-sexual BDSM. Had a $10,000 dungeon built in his basement, but his wife wasn't into BDSM. He only had sex with her, but had a stable of willing subs who would come over and let him beat the snot out of 'em.
So anyways, yeah, I get it that those folks exist. More power to 'em. But it ain't for me. My only objection to the two-year-old-discussion-that-I-am-now-bringing-back-from-the-dead is the notion that BDSM and sex are linked only because of Hollywood and "ignorant writers". Because I was combining those two things like chocolate and peanut butter nearly 20 years before 50 Shades of Gray ever saw the light of day. And there is certainly a rich and storied history of combining those two things in fiction (e.g. Anne Rice's Sleeping Beauty, The Story of O, hell even the Gor novels by John Norman).