Generally, if you want to find out what's popular right now, I'd suggest searching for the Oricon listing.
http://en.wikipedia.org/wiki/Oricon
It's a list of the current hits. You can even find some packaged torrents containing the last week/month/year of top 100 Oricon hits, if you're up for discovering random bands. It's less of a source for rock music than pop, but sometimes you can be surprised.
As far as rock-esque stuff goes, I'd echo previous posters' on The Pillows as being a pretty old school and famous band.
Have you tried:
- Plastic Tree (lead singer's voice often described as "ethereal" and "child-like", they say that they are heavily influenced by Radiohead and The Cure, but don't really fit into any genre - a really unique sound)
- Ellegarden (west coast style punk with copious usage of mostly correct English - this you gotta listen to just for the amazing English lyrics. Wow!)
- Ajikan (aka Asian Kung Fu Generation - album art is pretty sweet, music ain't bad either!)
- Bump Of Chicken (kinda more alternative-y, but it's hip with the kiddies over in JLand these days)
- Guitar Wolf (about as growly as a JHonJin's voice is going to get, wikipedia calls them "an energetic cross between The Ramones, rockabilly, classic punk, and noise rock")
- Southern All Stars (again, alternative/pop-y, and hip with the youngsters)
- Miyavi (pretty wide range of styles for this guy, so depending on what you find it might be rock or it might be acoustic guitar jazz covers, but still a good bet)
Here's a couple great sites for some other ideas:
http://www.rockofjapan.com/
http://en.wikipedia.org/wiki/Music_of_Japan#Rock_music
http://en.wikipedia.org/wiki/List_of_Jap...rock_bands
I hope that helps!
-amt
(edit: also, note that 'visual kei' mostly just applies to a style of performance, not a style of music, per se. It can be anything from pop to heavy metal to electronica, so long as they have the right style and presentation... so don't write off all visual kei stuff just because their costumes are weird. Remember that you can enjoy music without enjoying a band's looks or the subculture that they promote! )
Edited: 2008-07-30, 6:54 pm