I finished all of Hayato's route and the common route, up to where it branches off for the other! It was enjoyable and I found very few problems, but I'm going to get to before my more detailed opinion on the game.
Starting off, the only thing that really stood out during Hayato's route was Bad End 1. I had MC's name set to something different from Nara, but after MC faints, Hayato refers to her as Nara. In the common route, while paying more attention to Shuye and Haiyue, there are a few instances of repeated text, as if someone was changed text but forgot to delete what was there before. The part that was most memorable was when Shuye and Haiyue are explaining why they are there. Other than those, I didn't find many problems.
[Spoiler warning, just in case] I found Hayato's route a great balance between serious and lighthearted. The one thing I truly distressed over was the Spring Scene™, as I've been calling it these past few days. Its an important-ish scene, but oh boy, I get secondhand embarrassment really bad, so bad in this situation that I dreaded playing the game again. I sincerely hope that I only have to encounter such embarrassment again when playing Mikio's route, but of course, you're the creators, and I'll play whatever it is you put out. Besides that, the humor was good as well as the pacing, and the understanding that develops between Hayato and MC during the good ends and normal end seems realistic to me. Also that glimpse of Mikio during Bad End 2 was... interesting to say the least. I look forward to the release of his route.
I doubt I'll have much to add until the other routes are released, but I hope my review helps in some way.
(Also does the minigame really affect the story? I got a perfect run on it the first time around, so I didn't bother to redo it. Also it was cool seeing Auralee in it! But I haven't' a clue who the Smooth Gentleman and Elegant Soldier are, sadly.)