It was the very letter lying in his backpack.
Shen Yu repeatedly rewound to the period before the envelope appeared, and the moment it suddenly showed up.
The surveillance footage had gone black, as though it had been affected by something.
And the blackout had lasted only three seconds.
Shen Yu spent some time confirming whether the video had been replaced.
It had not.
This was the original footage.
It had not been replaced, altered, or deleted.
Then what had caused those three seconds of black screen?
Had someone hacked it?
Or had the signal been interfered with?
Shen Yu himself had plenty of ways to pull it off, but what he could not figure out was who had done it, and for what purpose.
Breaking into the school surveillance system just to deliver him a letter?
And three seconds—if someone had delivered it in person, there was no way they could have entered through the door, set down the letter, and left again in that time.
He had observed that the letter on the desk had been placed very neatly, not casually tossed there.
The later footage also showed that although the classmates who arrived afterward noticed the letter, they merely gathered around to take a look.
Or watched from a distance without approaching.
Even Wang Huan and the others had done the same.
Their real purpose had not been the letter. They had merely used it as an excuse to cause trouble for him.
Shen Yu's mind spun rapidly.
There were thirty-four students in the class.
Through their everyday interactions, even without deliberately studying or observing them, simply by sharing the same classroom—
the constant stream of information had allowed him to build a complete personal profile database.
If any of these students saw their own files, they