Nightmare (pronounced Naitomea) are a Visual-Kei band formed in 2000, Japan.
The members are Yomi (Vocals), Sakito (Lead-Guitar), Hitsugi (Rythm-Guitar), Ni~ya (Bass) & Ruka (Drums)
I used to listen alot to them sometime ago, but they kinda faded from my Playlist... Feels pretty nostalgic to hear this song now.
The song is Alumina, it was the ending song for the anime DeathNote, so you might know it even if you didn't know the band ^^