Mikado really does need to learn quickly that he's on the bad guy's side right now. Like, look, sure, you were raised in this system, you genuinely believe there are bad oni out there, I get that...but c'mon dude. Look at the people you're hanging around. The Momo gotta go.
It's funny they introduced the concept of the Momotarous having mandatory testing before killing someone only to show literally every Momotarou not bothering with it.
One way you could have included the counter thing in the translation: The Momo could say something like "I've killed 4 of these beasts!" Similarly dehumanizing, keeps the sentiment of the Japanese translation. Just a thought you might want to incorporate in the future.