Bijo no harawata AKA Entrails of a Beautiful Woman (1986)

Japanese sexploitation horror, with copious amounts of both sex and horror.

Opens with the drugging and brutal rape of a girl by the yakuza, who escapes and later commits suicide by jumping off of a building. The splatter of her body is depicted by smashing a watermelon in a parking lot. You might think this is to save money on special effects, but later there will be several splattered human bodies, so I guess not.

The nurse who treated her before she suicided takes revenge by drugging and kidnapping a yakuza member and hypnotizing him with a handjob. Perhaps the dead girl isn't really quite dead, but is somehow still alive through this nurse?

The yakuza do some gruesome stabby-stabby murders with sticks and swords, and there's plenty of Miike-like splatter and guts and leaking severed body parts.

It doesn't quite go as the nurse planned, though, and she gets raped and drugged too. The extra-strength heroin they use causes very unusual animated bulges under people's skin. Eventually the bulges escalate, and it becomes a full-blown mutant monster movie. More blood splatter is involved.

Japanese movies can't show real genitals without blurring, so they play lots of camera tricks to get as close as possible. This proves much more interesting than actually showing genitals. Though the blur does show up in some scenes for some reason, despite not looking significantly different than the uncensored ones.

The monster gets a truly obscene puppet dick, which is not blurred at all, and which stars in its own grotesque sex/murder scenes. If you've never seen a meter-long, lumpy, bloody, monster dick tear through the abdomen of a victim of sexual assault, here's your chance.

The sex scenes are somehow less gratuitous, though perhaps more intense, than in most european sexploitation films, as they actually play a pivotal role in the plot here. The plot also makes reasonable amounts of sense (for a rape-monster film), moves at a good pace, and is accompanied by decent acting and sensible camera work... all setting it well apart, in a good way, from the 1970s european counterparts in the same genre. More research is necessary to learn whether this is an aspect of it being from the late 80s, or of Japanese filmmakers taking more care in their work.