Ghost BJs could work, you just have to offer your dick at a shrine or something. Downside, you might lose your dick. Upside, if you're shaking your willy at a shrine hoping to catch some spirit's attention, you weren't going to use it anyways.
It only took 3 chapters to hit us with edgy backstory. You know what? I'll take it. Certain manga doing edgy betrayal stuff in the first goddamn chapter have lowered my standards quite a bit.
With one, it may have just stayed at that. But with two? The each and everyone in that school probably has some weird fetish. This is the law of weeb statistics.