On a rainy night, a lowly pastry cook (Yutaka Hayashi) lets himself get talked into driving a waitress imbued with a certain sukeban charm (Tamaki Katsura) who works at the same cafe as he does home. On the road, they pick up a strange woman dressed in something that looks like a hospital gown. Sitting on the backseat, she soon starts to cut herself with a knife and razorblades. Our nameless protagonists throw her out, accidentally killing her in the process.
Sukeban Gal convinces Cook - not that it does take much convincing, mind you - that it would be best to hide the body on a deserted junkyard instead of going to the police. Afterwards, they feel inspired to an enthusiastic bit of sex.
While he tries to avoid her the next day, she thinks that their shared experience is the perfect basis for a relationship. It's just too bad that he has performance problems if he has not been freshly aroused by a murder. What to do? Oh, yes, let's kill another woman. And then another, and another.
She thinks they are a perfect couple, and starts to act out her view of a perfect relationship, just with added murders, with him. What the poor girl doesn't comprehend is that her beloved (and it is love on her side, not much doubt about it) killer doesn't really need her anymore, now that she has provided his trigger. The act of killing has fast become much more important than the sex afterwards for him, it is in fact sex for him, and soon he starts to go out and kill on his own, getting more reckless with each murder.
Yasuharu Hasebe was one of the handful of Nikkatsu Studio's directors who stayed on after the Nikkatsu action phase had run its course and the studio invented the Roman Porn(o) film. His contributions to the latter genre like Assault! are all not very interested in being erotic, instead portraying emotionless psychopaths without much explanation of their backgrounds or histories.
This does not mean that Hasebe is completely disinterested in his protagonists' psychology - he just prefers to show us the last phase of a sexual psychopath's development, the motive behind his actions not exposited, but acted out, explained by the way he stabs his victims with a knife he likes to keep close to his crotch.
Hasebe shows the murders and the sex in such a clinical way that you'll probably have to be a sexual psychopath yourself to find much excitement or enjoyment here. Often, the film feels like a documentary gone horribly wrong, filmed by someone whose lack of compassion is equal to that of his protagonist.
It's all decidedly unpleasant to watch - as well it should be - yet Assault! is also something of a very black, very deadpan comedy, taking cynical shots at concepts like "the normal relationship" or a "healthy sex-life" in a way I found at once rather endearing and discomfiting.
What differentiates this from comparable American movies of the same era and unfriendly disposition is (apart from the lack of backstory that trusts the film's viewer to understand without being told) a budget and a technical professionalism most American indies could only dream of. This does of course lead to a certain lack of rawness in Hasebe's film, but the Japanese uses the contrast between the things he shows and the way they look to ironic effect. There's really not much that compares to a lovingly framed shot of a man stabbing a woman in the (carefully kept hidden by objects in the foreground) abdomen while 70s porno "da-ba-da-ba-da" music plays. Sure, a modern film would show us the whole act in loving close-ups, but that's not something I feel much of a need to see.
As accomplished and clever as it is, I still find it hard to actually recommend Assault!. It does what it sets out to do (leave the viewer squirming) excellently, but you have to be in a very special mood to appreciate it.