I've read most of Aji's works and they really know how to write Angst well. Currently reading Opium on Tapas and I'm looking forward to this On A Leash's return.
This is giving me Evangelion vibes with the way the story is set up. But the tits... Ogino. Please, sometimes I have to pause reading and laugh. They look like water balloons sometimes.
Just a theory but I think the reason why the Kaijuu's invading their world might be because it wants to be 'one' with the other body? Having two existing bodies will attract the other and idk...merge into a single body. Maybe the invasion means the Kaijuu will eat their own self?