Ok, so my theory is that the person called Takara is actually the puppet possessed by a demon. The boy is not a ventriloquist, it's the puppet who's talking. Like a Chuckie doll. The boy is its puppet, like a zombie, in order to make the demon look more... natural. I imagine that when the boy finally opens his eyes they will be in some way not human. Why I think it's a good guess:
- ventriloquism is lame
- foul mouth doesn't suit the cute boy
- the boy has never, ever been pictured in a panel without the puppet, which means, it could be the puppet who's the main character
- the puppet wears a school tie
- they often look like they were communicating
PS: I hope it doesn't count as double posting.