As far as I know, that building hasn't actually been used for teaching in years. It's a throwback to the days when the school was much smaller. Also, the other buildings around it are completely residential now, so I don't know who can have been living there, though it looks like someone was. The anime style graffiti is probably local teachers' kids or students. The shrine, though... workers, I guess. Other stuff included various kinds of alcohol bottles, lots of old motor oil bottles, one wizened, desiccated condom, little or no urine stink. I was hoping for junkie paraphernalia, but no such luck.