Mizu never goes to the theory room. Post a screenshot of her glossary if u can. The hint and the last played event. Also, world map hint would be useful too.
There wasnt a hint for mizuki on the map, sorry if that makes it harder
Think I've set this one incorrectly. Try going to the guard office instead.
Its fixed i dont know what i did but i fixed it, actualy i think all i had to do was proceed with either other stores or asara's story
Glad to hear it's resolved for you.