going on the japanese wikipedia page, he worked with 'nikkatsu roman porno'. it doesn't sound like porn as in 'hey, i brought you pizza and i'll fix your pipes and i'm also a naughty nurse'. creators had to stick to a couple of rules (one sex scene every 10 minutes and a running time of 70-ish minutes), but other than that they were free to do whatever they liked but within a limited budget. as long as you could work in people having sex, i guess. it's probably more softcore films with sex like you got on late night channel 5.
there's a database of their films online (they were made from 1971 to 1988) on the nikkatsu site, but the problem is that there's 1100 films to go through over that 17 year period. you can discount the early 70s ones since uematsu would have been in school, but it's still a lot to look through.