Yeah the first problem was kinda my own misdirection, so it wasn't a bug just the goal being a little unclear.
As for the final competitor, I had always left before 6pm I just can't leave after killing her (as I get a game over warning if I don't) as the button to go home again doesn't work. When I said even when it hits 6, I meant that time just keeps going and doesn't kick me back home or start an investigation. I can sit in the classroom to skip time but Sakura just stands there unable to move after. I'm not sure if i'm generally doing anything wrong?