I have some suggestions; not sure if they're exactly what you're looking for (this really isn't a sound I've heard much in Japanese music), but I think they come pretty close.
First off: yanaginagi. She's an anison singer, so most of her promotional songs are focused on that sound, but her b-sides, album tracks and non-major-label releases are big on dreamy and electronic sounds. I'll throw some examples behind a spoiler tag.
Spoiler:
Hoshiakari no Gaitou
Suzu no Tsunagime
Oto no nai Yume
Instrumental versions of all of these songs also exist, in case you want to try them.
And my second suggestion: Eiko Shimamiya. She's my favorite artist, so I may be blinded by bias, but I honestly do think she has some songs that might fit your criteria.
Spoiler:
electric universe
Taiyou
Onkalo
Binaural Beat
If you're willing to go outside of Youtube and do a little downloading to try things, I'd like to recommend going
here and downloading "Boffier ～木を植えた男～" and "Kite". Those songs are from Eiko's newest single JAIKO and I think they're some of the most dreamy stuff in her whole discography; they might be closest to the kind of material you're looking for.
Also, emi♡ recommended Akino Arai in another thread (
see here); from a quick preview, it sounds like she might have the right kind of stuff for you.
I hope some of these recommendations do it for you.