Honestly just kinda boring
We see a bit of like an everyday life of the characters, then someone gets killed, the girl solves the crime in half a day, rinse and repeat. There are no long lasting consequences regarding the deaths. The characters don't seem to get even an iota closer. Some mysterious subplot with the girl's past is getting revealed but I'm so fed up that I'm not even gonna read further. Also the annoying girl.
OH, and regarding that girl and the other characters. If a 40 year old male decided to marry a high school graduate, then... No one would fucking care. Here instead the characters are freaking out like she's not 18 but 12. Like really, I can't imagine this reaction considering how the Japanese are reserved.