Man, how nice of a random tiny mob monster to sneak up behind Hinako while Shiori is busy grappling with Emotions (do NOT give your fish Emotions! They interfere with the feeding process!) so Miko can pretend she's going to kill her buddy whilst actually chomping down on it.
Anyway, the whole 'Miko was captured by a monk and forced to serve as a pseudo-guardian-spirit' is pretty interesting because of the implications (I am obsessed with the worldbuilding of this series but also think it would be fine if Naekawa Sae never did anything to flesh it out and let us use our imaginations, following the honoured ZUN fashion of youkai-based storytelling). Like, I'm assuming this isn't the case for every guardian spirit in Japan and the monk was simply trying to benefit off a similarity between Miko and the present deity, but it does serve as one of those details that blurs the already-shaky line this series has between the human and inhuman even further. Humans venerate things more powerful and mysterious than ourselves, but in that very veneration, what we're worshipping, especially in case of faiths with a specific embodied deity, is something we've given form, a god in our image of the world who we believe has the power to affect the world in turn, a cycle of internalizing-and-externalizing meaning. Accordingly, the monk subordinates Miko and imposes their interpretation of faith and goodness over her natural instincts, forcing her to suppress who she really is. Because she's been rendered practically powerless by the monk, she's endowed by the people with a spiritual, symbolic power, made special in a faith created by humans precisely because of her impotence to truly show them how chaotic the world of the monsters really is.
It ties very nicely into Shiori's biting (haha) comment about the pointlessness of divine intervention, because she feels like religion is just another one of the pretensions humanity makes up to cope with the madness and cruelty of nature, praying to beings above them in the food chain for protection. To Shiori, it's merely another brand of foolery she can exploit to net herself dinner, but Miko actually seems to have believed in it, and thus represents a practical form of religion rather than an inherent one- divinity does not actually, materially exist, but good acts in the name of god shall bolster people's faith, until they conflate the benefits they receive in the name of faith with the benefits of the faith itself. While there's very definitely some monsters (and people, and religious institutions, and yeah, Everything is A Metaphor, actually) in Japan who exploited this by posing as gods and demanding sacrifices from desperate villagers anxious to dispel a threat that was in fact the monster itself, Miko is far more honest, and seems to genuinely derive a sense of purpose from her role as a spirit.
This might be either because she (as Miko herself would assert) has come to see the inherent value of human life and doesn't want to destroy it for her sustenance or because she (as Shiori would point out) needs to believe that her humiliation and captivity served some grander purpose, and fell into the same delusions that unfortunate people resort to in order to justify their sufferings as the work of a higher purpose rather than simply admitting they were forced into a shitty life, as the monk did to Miko. It's honestly a difficult argument to resolve, and emblematic of the moral ambiguity that runs through this series, but I definitely love how the perspectives of both 'monsters' are eminently human- Miko's assertion of a duty she must perform based on ideals nobler than the jungle (ocean?) law that Shiori runs on to elevate herself above the beasts, and Shiori's own scepticism in divinity and emphasis on living not merely as per your needs (unless Miko has been secretly snacking on outsiders for centuries or lying all along, she seems to prove that monsters don't actually need to eat people to survive and can either just endure or subsist on animals, other monsters, etc provided they accept the lack of flavour) but your desires.
Hinako actively moving to protect Miko is also remarkable in that it's one of the few actions she's taken since the start of the series that's truly assertive, the other especially significant one being her vow to carry through her contract with Shiori. Both of these are linked to her childhood, and I like how she symbolically ties Miko to the reason she's alive despite her family's death, similar to the way she ties her current reason to live to Shiori, because it drives in how Hinako sees life and death not as a strict binary, but intimately united, flowering in each other, best experienced in proximity- a near-death-experience makes you appreciate the value of life, being sole survivor of an accident saddles you with survivor's guilt and makes you wish you were dead, teetering on the brink of death makes you wonder if life was really all that bad, and, in accordance with Shiori's contract, living the ideal, most joyous possible life guarantees you a beautiful death. It's all a wonderful web of paradoxes.
At any rate, I hope I'm right about the cliffhanger being a fake-out and Miko being a character Naekawa actually intends to explore moving forward rather than unceremoniously butchering or transforming into a stock heartless villain, because she's too excellent as an individual and as part of the cryptid trio to erase or dead-end at such an early stage of her growth (also, her internal monologue midway through the chapter is consistent with her ideals rather than being absent, which does suggest that she's not lying her bushy tail off). Like, Miko and Shiori might end up murdering each other at the end or teaming up against a third, even crueller monster (imagine if Hinako ended up transforming into a demon due to the darkness in her heart and became the titular 'monster'), but at any rate, I need Shiori to unironically call Miko 'bingus' before either of them die. It can happen. It will happen.