I know that DragonForce is quite big in Japan
Amusingly, to my knowledge, metal is pretty big in Japan in general and the scene is very lively, and power metal specifically is relatively mainstream, I think. In a way, I think I wouldn't be surprised if DragonForce would be considered more widespread than Foo Fighters or Nirvana.
In any case, I'm a big fan of everything this story has shown so far, and hopefully, it keeps with it. Loving the uncle/niece designs in particular.
Apologies in advance for going off at a tangent...
There are a lot of heavy rock / metal groups in Japan which also get quite a bit of attention internationally - ones that I like include:
Band Maid
Nemophila
Lovebites
Mary's Blood (though going on hiatus)
Mutant Monster
Honourable mention to:
Kari Band (BOH and friends - more jazz/funk/fusion)
Esprit D'Air (UK based but definitely J-rock)
Anyway back on track... The uncle does have a little bit of a Dave Grohl look about him.
Really hoping that the story will continue after they get past the reveal.