'PM 10:07' is a 'Yoo Ji-min's text message' in White Day: A Labyrinth Named School (Remake).
It is exclusive to the PC/PS4 remake version.
You can see this message when you play the 'Yoo Ji-min' route.
It is found in the Messages Menu. (Mobile Phone - Gameplay element feature)
Something happened at your father's work, so we can't come this time.
I'm so sorry, Ji-Min.
We'll see you as soon as your father's work is done.
I love you.
아빠가 일이 좀 생겨서 이번에 못 올라가게 됐어...
일 마무리 되면 바로 올라갈게
사랑해 우리 딸~