If anyone could help me make one, I'll hug you to death out of happiness 
UtaForum.net
Mei-Saime
Mougeki Mero
I remember an off vocal of it on nico nico, but I cant find it anymore D:
You can try removing the center track from the onvocal, the audio quality overall will decrease but you could use an EQ to enhance it. The BG vocals might remain tho
You can try removing the center track from the onvocal, the audio quality overall will decrease but you could use an EQ to enhance it. The BG vocals might remain tho