Source of Trembling

In the dead of night, when people are quiet, Have you ever asked yourself, What is it that makes you tremble the most? The source of trembling is officially opened! (Note: The introduction has nothing to do with the content. Also, don't complain about the ugly cover. You will think this is better after a 2.0 Plus ugly version is made in a few days) Book club group: ②⑥ Zero Zero ⑦①⑨ Zero⑦