Mai Yamane (I managed to pick up this record in Tokyo, apparently it's very rare)
Hako Yamasaki (more folkish but absolutely beautiful)
Yoshino Fujimaru (aka Yoshino Fujimal)
Tomomi Sano (This one's pretty recent but it's fucking fantastic)
Hiroshi Suzuki (this one's more on the jazz side of things but I think you'll like it)
Anri (this is probably what you're looking for the most)
Kaoru Akimoto (opening a whole new can of worms with this one)
Tatsuro Yamashita (Minako Yoshida's long time collaborator, partner in crime, and if japanese conspiracy theorists are to be believed, secret lover - in fact, I'm pretty sure Minako wrote this song)
Makoto Matsushita (hell yeah)
Junko Ohashi (not the track i was looking for but i can't find the track i was looking for, sorry)
Junko Yagami (urgh the bass on this one is just insane)
Miharu Koshi (not really what you're looking for but it's maybe my favourite song of the lot, produced by Haruomi Hosono)
Chiemi Manabe (see above)
Yoshiko Sai (again, more folky but this record might have saved my life so please listen to it if you like this)
Yuiko Tsubokura (I think she's best known for anisongs but this is super dope)
and if you're not too knowledgeable about Minako Yoshida and Taeko Ohnuki, I really recommend their respective albums
Monochrome (1981) and
Mignonne (1978 - YMO are all over this record too, Sakamoto and Hosono are playing keys and bass on this track).