I think the timeline is as follows:
- first with the PE teacher in hotel
- then with the principal under the table
- followed by the episode with the principal on the table,
- episode with the principal and vice principal
- then the principal in the car park(two parts)
- with the PE teacher part 2
- and finally, the most recent episode in the library.
However, I think the timeline is a bit inconsistent. The episode with the principal and vice principal in the office seems to be a continuation of the episode with Akiha both under and on the table. So, the vice principal should already know about Akiha's situation. But in the car park episode, the vice principal is surprised to see Akiha. This is confusing because, although it wasn't explicitly revealed, the under the table episode implies it was Akiha’s first encounter with the principal. Also, in that episode (not really, it's a trilogy), the vice principal enters the office and joins in. So why is the vice principal surprised to see Akiha in the car park episode? Or, could it be that the car park episode came first in the timeline, followed by the episode in the principal's office?
If anyone can explain the timeline more clearly, please do so.