1. Select Chapter 2(The Haunted Buliding) - 'Wen Hua's Film Club'.

2. After completing the diagram, You will go to investigate the sourse of the crying.

3. You will hearing the voice of the ballerina ghost.
and A-Hai comes over and gives you the key.

4. But instead of going into the warehouse room, go towards the door where Wu Zi-nan was.

5. Then Wu Zi-nan will shout and you will get the achievement.

I hope this guide will help you 😀