>>43755371Even literal 70's hippies there like metal:
https://www.youtube.com/watch?v=hIjshrNAO6cNah, but seriously Japan is big enough a place that they can support variety of subcultures, metal is no exception. There even was a phase in the 90s and early 00s when old heavy metal records only got CD re-releases in Japan and you had to figure out how to import them or pray the second-hand store next town over would have the first and only press of the vinyl. Praying Mantis even got signed by Pony Canyon and kept releasing Japan-only records after NWOBHM died out back in UK, some others may have done the same.
That said, others have already recommended most of what I know. Ningen Isu is great and have 21 albums, so there's a lot to go through with that alone. Didn't see anyone mention Sabbat, which I'm not personally all that familiar with, but is regarded as something of a classic if you're into black/thrash type of stuff. Loudness on the other hand is The Classic JP Band from the 80's:
https://www.youtube.com/watch?v=RvyW_mbF1Yw 
