I originally started listening to Japanese music in 2005. A friend of mine at the time let me listen to Gackt, Hyde, and Miyavi and I was hooked. I found the other bands I like through research. 90% of the music I've listened to since then has been Japanese, but I also listen to Korean and Chinese music now as well. The Japanese bands I listen to the most are L'Arc~en~Ciel, D'espairs Ray, Dio-Distraught Overlord, 12012, Baiser, Exist Trace, Aikaryu, BLOOD, Ayabie, Calmando Qual, The Candy Spooky Theater, Duel Jewel, Mix Speakers Inc, Due le Quartz, Malice Mizer, Moi Dix Mois, Lareine, GPKISM, Schwarz Stein, Inugami Circus Dan, Janne Da Arc, Acid Black Cherry, Kagrra, MUCC, KuRt, LM.C, Phantasmagoria, Psycho le Cemu, Sadie, Shelly Trip Realize, Versailles, and UnsraW. The full list of what I listen to is on my myspace if you guys have one and want to add me:
MySpace - www.myspace.com/17809032
I found all of the bands I listen to on my own except for the first few. And I got hooked because none of it sounds anything like the American music I was listening to at the time (stuff like Evanescence, Kittie, Jack Off Jill, Otep) and there are some truly incredible voices in the Japanese music scene. And the Japanese language is just incredible and beautiful to listen to. I very rarely listen to non-Asian music and haven't for nearly 5 years :P so I'm a little behind on the music in my own country.