It's weird, I've never really wondered why there wasn't a JPop thread on this forum, but now that it's here, I wonder why we've never had one before lol.
My top Jpop acts are KAT-TUN and Koda Kumi, but I think I listen to quite a bit of it, just maybe not the super ridiculously popular acts that everyone seems to like, i.e. Arashi, Kyari, that AKsmthsmth group.
Other faves with high listens:
Yamapi
Namie
Lead
Ayu (only like older Ayu though)
KinKi Kids
Capsule
BoA (I guess she counts, she has lots of Japanese releases)
Hitomi
Mika
Tommy
ONE DRAFT
Every Little Thing
Perfume
Lecca
Yulia
FEMM
Chemistry
Sekai no Owari
Dream
Tbh, I probably listen to more Cpop artists, but I have more favorites in Jpop, if that makes sense.