SIDEROS: Their main genre is metal. They first met Kessoku Band in Volume 3 of the manga through an introduction by Kikuri Hiroi of SICK HACK, and have been interacting and exchanging with them ever since. Since the members are all in their late teens to early twenties, they share a similar vibe. They play a major supporting role in this work.

They debuted much earlier than Kessoku Band and have steadily built up their recognition, so they are currently popular enough to hold one-man live shows. Their albums are selling well, and SIDEROS songs are even registered in karaoke systems.