Readers would doubt whether or not Kuro truly loves Iwanaga, and I get that, but it's funny to me that Rika think the opposite. To Rika, Iwanaga only uses Kuro for her duty as the God of Wisdom (take note that even Iwanaga could not argue with that). Kuro and Rika's existence ruins the natural order, so it makes sense to kill Rika, to which is what Iwanaga's trying to do throughout the story, but the same applies to Kuro, would it not? Rika thought that Iwanaga would not fear killing or more specifically, sealing both of them, and she's not even scared that she doesn't care at all. What does that say about Iwanaga? "If you have any shred of humanity left in you" Rika cleverly used Kuro against Iwanaga, manipulating her into thinking that she would not care if Kuro disappears as a part of her duty. Rika led her into thinking a scenario where Kuro disappears and guess what? Iwanaga is mortified, thus collaborating with Rika in the end.
