When you set foot in Abandoned School: Every time. Only when you play the Student.
Details1
You say one of these
1- "The classroom numbers are the same as the building where I used to study... except the bell will never ring here again."
From the game files2
ThinkExplore 602
| ID | 602 |
|---|---|
| ChapterId | 1002 |
| TriggerType | 1 |
| PlayerSelectId | [2] |
| Rate | 1 |
| RandomThink | ["EnterExplore_School_NG_1"] |