Unlike most other casual threads, this one is supposed to, hopefully, remain open constantly for whoever wants to use it, instead of making an individual thread each time. Your character may be a student, they may be a teacher or part of the staff in general, or maybe some guy who somehow got in while NPCs don't really bother to stop you. Whatever the case, here's a setting. Considering there's so many High Schoolers running around, this may work. So feel free to use it.
Hidden among the many skyscrapers, streets and parks, maybe even the convenience stores, there is a beautiful building of three floors and painted in white. The front yard is ample and surrounded by giant trees with benches underneath, as well as neat paths taking the rest of the park-like area around the main building, popular spots for students who want to relax in the school ground when the weather is on their side. From here, it is easy to reach the main entrance into the main building, where all the classrooms are placed.
The first floor is about what one would expect from a traditional high school; leading to the backyard and having at least three different classrooms on each side of the building, all belonging to first years; the walls looking to the backyard all with windows that allow for a better view back. There’s also a single Store offering snacks, drinks and lunch for those who can afford it, and get there in time for it. Finally, the Nurse’s Office is in this floor, as well as the Principal’s Office.
The second floor is more of the same, this time for second year students. Besides that, the Teacher’s Lounge is located here, right in front of the Student Council Room.
Then, the third floor, belonging to those going through their third and final year of high school. The library is located in this floor, being quite massive for all those students that would rather read, study, or keep a low profile in silence.
Finally, the rooftop. Not many go there, but those who would rather be alone with no one else looking. It’s popular with lovers and close friends.
The backyard is quite spacious, similar to the front yard leading to two places: The Gym Building and the Practice Building. The first one is merely a gym, meanwhile the second one is centered around the activities and school clubs students themselves form. There are many different clubs in it, so much so anyone could probably make one up if they wanted to.