This was written by Zhang Nana, and "he" should be her boyfriend Peng Yu.

It's not hard to tell from the words that Peng Yu seems to have found evidence that Mu Zihan secretly filmed certain videos, and is using this to negotiate with Mu Zihan.

The negotiations failed, and they were instead threatened by Mu Zihan. It's important to note here that Zhang Nana and Peng Yu likely had a disagreement somewhere, which ultimately led to Peng Yu leaving.

What happens after you leave?

Looking at the diary, Yan Qing suddenly had a bold guess.

She opened her laptop and glanced at the calendar. It clearly stated that last Wednesday was the 2nd.

It seems that Meng Fan was telling the truth; Peng Yu must have disappeared that day.

However, there was one thing she really couldn't understand: if Peng Yu was missing, what about Zhang Nana?

Where did she go? And who was that woman who kept pleading for help?

Yan Qing was lost in thought until her watch vibrated. She then realized it was almost 9:40.

I opened my laptop, and the screen was completely black. At 9:41, a link to an online course video suddenly popped up.

Yan Qing clicked to enter, and a deathly pale face suddenly appeared on the screen.

His face was as thick as a pancake, his features squeezed into a slit, almost unrecognizable unless you looked closely. Thankfully, his mouth was opening and closing, making it barely recognizable as a person.

The shock was so great that she didn't fully react until the teacher in the video started the lesson.

—This was actually a Chinese language class. But the language being taught was one she had never heard of before.