Gao Yang wasn’t too surprised. Indeed, it was Yellow Butterfly.1

She had come up to the rooftop after checking the classrooms. Standing before a three-meter tall water tank, she lit the wall with her flashlight and seemed to be looking at something, engrossed.1

“Have you found anything?” Gray Bear greeted her.0

Without turning around, Yellow Butterfly stared at the wall and said, “No. We searched the school inside out yesterday.”0

“Then what are you looking at?” Gray Bear walked up to her to look at the water tank wall with her. “Oh, this is where people left messages.”1

Almost every school had a few comment walls like this one. Students would leave messages with chalks, markers, paints, or other writing instruments where...0