Yu Bai entered Lu Chengsan's dark corner and discovered his secret! In order to get him to give up this dangerous idea, Yu Bai "monitored" Lu Chengsan all the time, just in case he did something terrible. With the appearance of Lu Chengsan's high school classmate, their lives began to slowly change. As DAY Association members continue to disappear and get injured, Yu Bai gradually realizes that the truth of what happened five years ago is far more terrifying than he imagined.
How should they respond to the increasing number of "Dark Corner Expanders".
Concept: Everyone has hidden "secrets" in their heart, and the place where the black secrets are composed is the dark corner of the soul, which will expand as people's "evil" desires accumulate, thereby eroding the soul outside the darkness.