For who appears to be the main antagonist of the film:
Aigami will be voiced by Kento Hayashi. Notably, he hasn’t done any animated movies or TV shows up to now but he’s been in plenty of Live Action TV shows and movies in Japan.
Essentially for those wondering what that means, it means they hired an actor (that the general public in Japan is likely to know) to voice Aigami to give the movie additional star power.