Wait.
Nagano in the first chapter said that he wanted to turn into a small and cute creature, and then put a silly hat and get compliments.
Nagano insert isn't Chiikawa, it was Momonga all this time.
I love how Parabellum was THE Evil guy behind the scenes that we saw 8 years ago.
And the only clue that we have now about him, it's a wee lad with the same name.