I think I get now what you meant by 'you're not capable of writing happy stories', but this is something else, mah dude.
Were this real, one would probably be close to an emotional breakdown like Cooper in "Interstellar", when he sees the life of his children unfold without him, without him being able to do anything about it.
The setting is certainly grim enough, perhaps the grimmest that's been set in this canon so far. Even the Grounders in my story are way happier with their life and purpose than the ones in Manila. I study sociology, and from that perspective, I find this even more horrifying. Beliefs spread along social networks, but it doesn't seem like everyone in this third-world society believes in the Kaijus as gods, as this protagonist does, especially since he's… not being taken seriously by his family after coming back as an 'apostle'.
Without this kind of reinforcement, a religion usually (also) relies on, it can only be left to imagine how grim the character's surroundings must truly be. I don't know if that was your intention, but it does make the whole ordeal look almost like a psychological flight into fantasy. I almost wonder whether he really interacted with that Kaiju or whether he's imagined even that.
The only thing I found hard to grasp is the wider situation in the world here. You probably left that out intentionally, but I do wonder what the Kaiju is being sent to fight and whether a war is going on, and with whom. Would have been neat to have at least a hint.
This story is uncompromising, it's harsh, it's a +1.
All the best
- Nylo