As a general rule, Japanese rock bands are pretty great. If they are psychedelic in any way, they tend to be completely fucking insane and heavy.
I by no means pretend to be an authority on this. In fact, I'm still listening through albums by a lot of these bands. But the scenes (at least the psych scene) seem to be pretty insular. A lot of these projects share members, and if you like one, you will probably like the other. For example:
These guys are fucking nuts. Keiji Haino is a guitar god and is the main dude. He has played with all sorts of other bands, including Boris. Fushitsusha make really out-there improvised psychedelic noise rock. I mean, watch these guys jam the fuck out:
This is a little less freeform, but equally awesome:
These guys, Les Rallizes Denudes, do the Spacemen 3/krautrock thing really well, only they were doing it in the 1960s and being totally fucking batshit back then. This video is from the 80's.
Some of these groups do the Blue Cheer/Sabbath thing really well. I'm sure most of you are familiar with Boris. But there are also great bands like these, most of which are interconnected in ways I don't want to explain right now. they were doing the lo-fi thing before it was fucking cool to make shitty-sounding records. The other difference is they fucking rip on their instruments:
Sometimes the bands get kinda pastoral and mystical and shit. For example:
White Heaven's Michio Kurihara has also recorded with this band, Ghost, who are totally fucking amazing:
Plus Boris and a whole bunch of others.
Then there are bands like Acid Mothers Temple, who are kind of a combination of all of those things:
Marble Sheep are fucking amazing as well:
Basically, these bands all destroy. I'll post more later.