I second globe. I only got into them 2 years ago or so, but they have alot of great tracks, i love genesis of next

For electro J-Pop I can recommend

- MAA
- Kyary Pamyu Pamyu
- arisa
- sifow
- Akina Nakamori (but only her album "DIVA" has electro influences)

and of course Mizca, but she has been mentioned before.

How about Genki Rockets? Don't know if it counts but i love them haha

I forgot about Genki Rockets as well, they're great indeed!

definitely +1 for genki rockets and m.o.v.e!

MAA is really great! Love her! Since channy (I love you for this! :heart xD) introduced me to her, I never deleted her from my mp3 player. I'm addicted!

EDIT: You already know of perfume.
However, may I suggest the album "Yellow Magic Orchestra" by the Yellow Magic Orchestra.
It apparently is a pioneer of electronica in Jpop.

Spangle call Lilli line is absolutely BRILLIANT. I would definitely classify them as electronica, but not in the same way as Nakata Yasutaka's acts or anything. Their stuff is a bit 'quieter', lol. Anyway, they have a substantial discography, but their album PURPLE is a masterpiece.