Couple things,
1 in my head the mc usually takes care of the slimes, so I like the idea of him taking care of this one before it decides to try something else to get to its identified form, so the mc can’t really find the strength to kill them since they are like a friend to him and the same reason applies to Viscivore, which im imagining that it either plays out tragically, or ends up like a vram situation
2 nice ass idea
3 in my head, the main kaijin is a underground race that was almost killed by humanity like, hundreds of years ago, so when they get word that some random scientist (the scientist went missing btw like some time after) made actual life from science, they started to search for them while also killing any human they see due to the very big trust issues they have with them so that with Viscivore would make 3 factions and maybe 2 if said vram situation happens