It's haunted

"Why not?" asked Charm.

Realizing that she was squeezing Charm's wrist too hard, Serene finally let go, then shrugged. 

"It's a memorial stone to commemorate the deaths of students, who died on school property."

"That's quick, they put up one for the demon locust invasion already, so fast," said Charm.

"No, it's for an incident that occurred way before the world even became aware of demons," Serene answered then stopped talking as if she said too much. 

Charm gave her the pleading eyes look as if to say keep talking but Serene went mute. 

"Oh come on, it's been years then why are you so pressed about it. Surely, you can tell me what happened or do I need to go over to that memorial slab and do some digging on my own then."

"You can't say I didn't warn you but to go over there would only invite misery into your life."