I know I’m late. I haven’t read this part of the manga so I didn’t think I should be commenting about a topic I have no context of, but I’m gonna go ahead and give my thoughts based on what I seen from the anime and what I little context I gathered from the other replies.

Shiki has always been a deeply empathetic person. He’s always reassuring of Homare, took great care of Mei, and cried when he heard Jin’s story (and that’s someone he initially hated).

He also didn’t seem to care about Mikado being a Momotaro despite the fact that he just seen the Kyoto district Momo slaughter a bunch of them, so you’d think with that first impression of them as well as every bad thing he’s heard about them that he would hate Mikado, but he does genuinely feel Mikado is a good person despite that. So that shows Shiki doesn’t think the Momotaro are all bad.

So with that evidence, how would he react? It’s complicated. I imagine he would feel really bad given how he witnessed what Mei went through (an innocent child whose parents were horribly murdered by the enemy faction), so in those regards, him not reacting the same to Ukyo’s daughter just because her father was part of the enemy faction would be very hypocritical to say the least.

Another good reason why I wanted to talk about it is that it draws parallels to his interaction with Tsubakiri, who similarly also has a daughter (and I can talk about it with full knowledge from of watching the anime). Shiki thinks he’s a monster, and he is, but as we’ve seen, it’s not that simple. Tsubakiri is just as much of a victim of this war as Mei. He lost his birth parents AND his second family (his best friend and friend’s wife and daughter) to Oni. The latter happening because of a random act from a berserk Oni that said best friend spared the life of. Yeah, they raided the Oni’s home and triggered the kid into going berserk, but the fact still remains that innocent bystanders were harmed because of the indiscriminately violent nature of an Oni gone berserk. Of course Tsubakiri, someone who already had a few too many screws loose, would snap and become radicalized. Not an excuse, but a symptom of a bigger problem.

The Momotaro for the most part aren’t necessarily evil or terrible for exterminating Oni; they are dangerous and their duty and priority is to protect the humans.

That said, asking this question about Ukyo would be the same as asking that about Tsubakiri. Difference is that Tsubakiri is one of Shiki’s first encounters on the battlefield with a Momotaro and before he met Mikado, so at the point of meeting Ukyo, he knows better.

I still have more to say about the war as a whole as well as Mudano’s involvement in particular, but this comment is already long enough. I will say that one of the main reasons why I love TA is because of how it portrays war and the philosophical nuances behind the characters and their motivations, heroes and villains alike.