Remioromen レミオロメン Ikimono Gakari いきももがかり Mr. Children/Bank Band Yui Ikue Asazaki Asian Kung Fu Generation ... there are some more, but these are the singers I love most.
I agree, asian kung fu generation is an amazing band. they're pretty popular too. they have amazing and catchy songs and songs you can just sing along to or listen to when your not in the best of moods. i love them.
I have a lot of different songs and japanese singers that I love. So to list them all is too much trouble and not only for me xD.
My favorite artist is Yui. Some of her songs:
Rolling Star - Some people may recognize this song *cough*Bleach*cough* ^-^
Tokyo - It sounds very sad, but on the other hand (if you find the lyrics) it's also a happy song ^-^
Life - Bleach ending song ^-^
ChE.R.RY - It's subbed...am I nice or what?
Since I love a new song every day... here's the latest:
They were mentioned before: Remioromen (レミオロメン) - Sakura