Tomoyasu Hotei - I don't really listen to this guy that much,but his stuff is really awesome and his song on the first Osu!Tatakae Ouendan,Thrill,was what really got me into music.Then I heard his cover of Rocket Dive and I started listening to this other guy
hide - The day I listened to Hotei's cover of Rocket Dive is just something I'll always remember.I saw the guy in the video and I had to know who he was.Then I started listening to hide's stuff...and by some incredible coincidence,the hide memorial summit was happening on those days.So,in those days I listened to Dir en grey,MUCC,D'espairsray,Luna Sea,X Japan,and lots of stuff.I also downloaded the Hide Tribute Spirits cover album,and listened to Buck-Tick,Kiyoharu and Kyo(D'erlanger) for the first time.I fucking love you hide.
Dir en grey - My favorite band.What else can I say? First listened to them in the hide memorial summit...was a bit shocked at first.Their stuff was too "heavy" for me.Months later I listened to I'll and then slowly managed to like their entire discography.
Nine Inch Nails - One of the first not japanese bands I listened to.Got me into industrial rock and industrial metal.
Buck-Tick - The variety in their albums...just incredible.I listened to all their albums...and every album they released had a different genre.So I went out to find what was stuff like post-punk and new wave.Those are two of my favorite genres now,so thank you Buck-Tick.
Metallica - For getting me into thrash.Later I started to listen to speed and black because of thrash,so...yeah.
Alice in Chains - made me listen to the whole grunge scene and also to Drone and Sludge metal bands later.
Balzac - Someone compared Dir en grey's Child Prey to this.As I loved the whoah oh parts I had to listen to it.
Misfits - another of the first not japanese bands I started listening,met them through Balzac.Got me into punk,and 50s music.
And these days I listen to almost every kind of music.