In a sense, Ibaraki-dōji is considered one of the high-ranking members of the Kamiya Forces at this stage.
She has the right to be informed about these matters.
Moreover, aside from Hoshiguma, Kamiyagawa himself occasionally visits the Ibuki Daimyojin Shrine to see Ibaraki-dōji and talk about the outside world.
He also brings some sake as a gift for the black serpent form of Shuten Douji.
It's a way of fostering a relationship with Ibaraki's brother.
Ibaraki-dōji, like a noble lady, sits elegantly in the center of the shrine's main hall, but beneath the white hood, her delicate face carries the roguish look of the Ghost Tribe. Especially when talking about Kamiyagawa, this expression becomes more pronounced, and the corner of her lush red lips curves into a slight smile:
"Hoshiguma, you say that guy Kamiyagawa is preparing to head to Yomotsu Hirasaka? Hmm... no wonder he hasn't visited me for a while, which has indeed made me a bit lonely."