I'm going to date myself with this post, I just know it hehe
I can't stomach a lot of J-Rock and J-Pop.
I like folk music, Okinawan music, indie rock, punk, and anything I can sing along with easy.
My list of Japanese bands currently on my i-pod
長渕剛 - Tsuyoshi Nagabuchi - kinda like a Japanese Bob Dylan, Springsteen or John Cougar Mellencamp
The Blue Hearts - Japanese punk at its best, gives Sex Pistols, the Clash, and the Ramones a run for their money
河島英五 - Eigo Kawashima - a bit like a Japanese Billy Joel, I recommend お酒と泪と男と女 - a sad drinking song.
BEGIN - best Okinawan band around
Orange Range - probably the second best Okinawan band around, the 2nd volume of their greatest hits "Range" is crazy good
HY - another Okinawan band, friends of Orange Range, and awesome in their own right. I recommend Song for... from their album Trunk
Sodopp - I really highly recommend their album Pop Rider, I like it better than Judy & Mary
Shoukichi Kina & Champloo - Classic okinawan band that you can find on iTunes. Their song ハイサイおじさん is an all time classic, as is 花 (すべての人の心に花を) - which is one of the prettiest songs I've ever heard.
スピーツ - Very 80s sounding band from the 90s. My wife loves 2 of their songs, esp チェリー
Southern Allstars - another classic Japanese band. I rank 'em somewhere around Jimmy Buffet or the Eagles - they've had tons of #1 hits. I like their いとしのエリ
Mods - another punk band, big in the 90s, you can get 'em on iTunes. Imagery similar to Social D & psychobilly stuff, music a bit in the vein of the Ramones.
夏川りみ - Rimi Natsukawa Okinawan singer. her version of 泪そうそう is one of the best
Rinken Band - Hard core Okinawan music; may not be for every listener, but they are critically acclaimed.
ケツメイシ - These guys from Tokyo are just fun. Not a big fan of Japanese hip hop; but these guys have such a nice groove going in all of their songs it's hard to think of it as hip hop.
Bennie K - My brother-in-law said he listens to nothing but this band. They're kinda fun once you get used to them - 2 girls. The singer is very much in the vein of Kelly Clarkson. The rapper chick got into rap when she was studying abroad in Cali & fell in love with Tupac's music. Most of the rap you'll probably want to ignore, she's like 50% fergie, 50% tha brat, 100% annoying with her gangsta type lyrics via a mall-rat-sounding delivery. Still do like some of their songs.
TRF - the only Jpop band I ever got into. Survival Dance & Boy Meets Girl take me back to 90s nostalgia.
Rize Japanese Rage Against the Machine.
B'z - remind me of Bon Jovi for some reason - but much better
X Japan - in the 90s, this band could give GnR & Metallica a run for their money
Hide - Guitarist of X Japan, died in the 90s, but left behind a very good album that is very much in the vein of Ministry
Pizzicato Five - a great Jazz band.