Good on you Mira, earn that belt the right way and enjoy the process of learning. I do really hope that look from the professor doesn't imply something sinister, but it could be interesting if it turns out he's connected to the sealed monster Haru's dad mentioned a while back (the one the family seeks to be prepared to beat should it ever escape.)
I feel like things will either end with the professor turning out to be part of the monster sent to release it (and that's why he wants the belt,) or it will be the professor's duplication of the belt that allows the town to defeat the monster 🤔