Started off weak but picked up pretty quickly once the schoolgirl stuff started. But please remove some illusion of choice things like the poll - it doesn't even give new scenes.
Some things I want clarified though. Did the Nurse actually develop the pills? Are the pills and drink actually magical?
Oh, and the MC should be 18. 20 is too big an age gap for his old schoolmates to still be in high school imo.
The pills are not known who developed them, the drink is not magical, but they call it that because of the immediate effect it has.
In my country, high school is up to 18 years old, at no time is it discussed where the story takes place, so it is possible that the MC continues to be in contact with people who continue to go to that school
It depends on the campus. Some of them have specific visiting days, but otherwise you can just waltz into them. Public universities count as public property, and if the doors to a "hall" are unlocked and you look like a student it's fine. You can't just go into a classroom, but a lot of classrooms have windows you can easily walk by and take a glance inside. Regardless, you can always just go to youtube for video'd lessons of professors and see how college classes look and work that way.
Plus, as for public universities, they have things like shops, banks, cafes, etc that are totally public. My uni had one of each of those and a salon literally right next to each other and anyone from outside could easily walk to them. Only using certain facilities is restricted, ie libraries and gyms, and of course dorms are private too.
