far fetched headcannon time: What is Defoko hates Momo because Momo was made to be Defoko’s replacement? Think about it: Defoko was the first Utauloid, and has a rough, robotic voice that’s hard to work with. So, Momone Momo was made to replace them, having a cuter, more original design, a nicer personality, and more realistic voice. Knowing that they have effectively been outshined, they actively bully Momone Momo and take advantage of their kind personality. Maybe Momo’s detachable head was made to be an emergency getaway mechanism, something that Defoko does not have (hence why they steal it). Defoko isn’t really known to be mean to anyone but Momo, and generally wasn’t portrayed as mean before Momo. It’s all just jealousy.