basically, you're gonna need to be on a private tracker to find a lot of the good ones. but essentially, here's a few lesser known (relatively) good ones.
shinya tsukamoto's movies, such as tetsuo: the iron man, or tokyo fist. both of them incorporate elements of body horror and hyper stylized editing, kind of like a cross between david lynch's eraserhead and something like a hiroyuki imaishi anime... potentially if you're willing to stretch it that far.
nobuhiko obayashi's movies, he has a lot of good ones, but start with house (1977), which is a cult classic. then you can watch some of his other 80s movies like sabishinbou or his motorbike, her island.
movies by director hirokazu kore-eda, a popular director in japan, one of my personal favorites... one of my favorite movies by him is air doll (2009), which is about a blow-up sex doll that "gains a heart" and comes to terms with living within a repressed society.
someone like sion sono, known mainly for love exposure (2008), an over-the-top four hour experience. if you enjoy love exposure i would recommend watching himizu next, though be warned sion sono is a bit more outlandish compared to other directors listed here.
akihiko shiota, check out the movies "moonlight whispers" and "harmful insect"
here's a few more:
bounce KO gals, love & pop (and shikijutsu, or ritual by hideaki anno), and a lot more. you get the point. there's a lot of great japanese movies, hope this list helps.
