I’d like to borrow the expertise of the forum to help me out with a quick question, if I could. A while ago I was shown a clip from an anime series where a kid is being picked on and goes to an abandoned building and starts playing his guitar to vent his frustration. After his guitar playing (why I was shown the clip) ends, some demon/vampire appears and tells the kid that “music won’t help you solve your problems, only revenge will do that, and I can grant you the power to exact it”, then the demon thing transforms the kid into some sort of lesser demon lackey.
I’m pretty sure that the show came out between 2004 and 2007. Would anyone happen to know the name of this series?