Yeah, it feels really tropey. I think every shonen reader has had enough of these quirky villain groups since like 10 years ago. Maybe he'll kill em all off in one scene like he did that masked dude's team to make it less predictable? Would be a neat way to show just how much stronger the blades are than regular sorcery. The worst option IMO would be having them fight blade users 1 on 1 and making it a whole arc.
On another note, I feel like he should have shown Japan refusing the demands on the island. Bet there was a fight. Although I'll forgive him if he off-screens the Soga leader in that fight.