The Power of Crystal

Exploration Stage: Heirs' Villa
From: Kira Woodville
Description: The fact that there is nothing wrong with the door suggests that the culprit must have snuck in through the window. No shards of glass seem to have fallen, but the murderer must have been very careful. I'll check this window here, and you check that one over there, please.
Completed: Yes, it is. The windows of the mansion are made of tempered glass with crystal chip alloy. It is impossible to break them. Also, all the windows were tightly closed. Only ghosts can pass through here...