Guys, listen, like, really listen to me:
If I was in Kotarou's position, Puniru would had become human long time ago. Why?
Because I'd feed her MY thick and goey white slime on daily basis. Fuck soda, borax and whatnot. Her diet would only contain my raw release, my precious essence,... which also full of my very own human DNA.
And as you've known, Puniru would change according to what she consume, so it'd not be a stretch to say this is the MOST viable way to turn her from a slime into a full-fledged human.
Your thoughts?