Was thinking more about why the Hinagiku might hide Kurogao's identity from Taiyo, and I wonder if one aspect of the decision to hide it was that Kuroyuri/Kurogao knows about the Hinagiku, so it was better for Taiyo to go in blind.
Rin tells Taiyo that they can't send any of their agents because Kuroyuri knows about the Hinagiku. I can't tell whether the Hinagiku really believes that or if Rin is just hiding the real reason they want Taiyo to go undercover.
On the one hand, it's true that a high-ranking government official like Kuroyuri would know about the Hinagiku. On the other hand, you know who else would know about the Hinagiku? Kurogao. That guy was a hotshot assassin working for all the big names in the government—there's no way he wasn't intimately familiar with the government's personal spy service. In fact, it's possible that he's been on the Hinagiku's shit list before for that very reason.
And if they suspect that Kuroyuri is really Kurogao, then he would know all about the Hingiku anyway, and would probably also know all of the Yozakuras as well—he clearly knows enough about them to counter their techniques. Taiyo is a relative unknown and might be able to take Kuroyuri/Kurogao by surprise.
There's also the fact that Taiyo is a rookie spy, one who's barely been in the field for six months. As much as they like him, they can’t assume that his marginal experience on missions is enough to trust him with such a big piece of intel. The whole mission is basically Kurogao and the Hinagiku playing chicken—Kurogao pretends he doesn't know about the Hinagiku, the Hinagiku pretend they don't know Kuroyuri's true identity, and they're waiting to see who flinches first. Telling Taiyo automatically puts that gambit at risk, because the Hinagiku don't know if Taiyo can be trusted to keep Kurogao from discovering that secret (and like. to be fair. Taiyo WAS throwing around documents and ripping into boxes like a hungry bear so it's not like this caution is unwarranted lmao).
So while it’s possible there’s another reason for the secrecy (they didn’t know it was Kurogao until later, they had orders from above to keep it hush-hush, etc), I understand why they might be reticent regardless. In a lot of ways, this mission feels like it was the Hinagiku testing Taiyo—they wanted to see how he would react in the field, his strengths and weaknesses, and whether he would be a team player. No matter what the reason for not telling him, the mission was ultimately a success and I think Taiyo passed the test with flying colors. So no harm no foul I guess.
