Firstly I have to say it's kinda funny and I guess also planned by the devs that it took 12h to finish it.
So to start the characters are great. The design is maybe not the best (but is still a personal preference) but I can't ask for more if it's F2P. What I'm not that much of a fan of are the background images. Sure they got a filter and some look good but most are really bad (I Hate Real Life images in VNs). If we talk about the puzzles they are okay but it feels like some are way too easy and some feel nearly impossible to solve,,,, The Story is nothing special but it works and I don't think it's that easy to predict what happens. What I hated the most is the class trial because even though it was so simple it felt like a lot of stuff that made sense is wrong and your only option is it to get the correct answer through trial and error :/

Overall it's a great VN and I recommend everyone to try it out (I mean it's free so you have nothing to lose)