It's cute, don't get me wrong. It's kind of hard to point out the flaws without spoilers.
The main character is slightly annoying. I wanted to like her, I did, but I feel like they didn't really try hard on her personal, at all. I swear I've seen a version of her (hair color/height/skin tone/sass) in a good 6 anime shows.
The guy in the mask is just beyond weird; enters and exists and ...