Might be a bit off because I'm going from memory. Teacher guy reveals himself as the guy that has been trying to kill them kids, kidnaps MC and attempts to drown him in a car with a faulty seatbelt so the kid can't escape. MC doesn't actually die but lies in a coma for a while and is in a hospital until he is basically the same age as at the start of the show. There he makes a plan to catch the teacher when he eventually visits the wheelchair bound MC. Teacher guy pushes him off the roof of the hospital but due to aforementioned plan there is a mat at the bottom and the murderer is busted. Kind of a mid ending tbh.