"Let's swear that we will die together on the same day and at the same time. When someone reneges, we must promise again that we will complete the death task in other ways. " Late at night, in a high school church, three girls (You Zhen, En Ying and Suyi) each held a lighted candle around the letter of commitment, cut their fingers and made a declaration of friendship agreeing to die together. That night, Yan Zhu (Jang Kyung A) committed suicide by jumping off a building on the roof of the Life Museum. At that time, my sister Chongen (Yu Sin Ae) happened to pass by the Life Museum and witnessed all this.

There are various versions of speculation about Yanzhu's suicide. Among them, Suyi (Sun Enshu) used to be close friends with Yanzhu, but later she began to stay away from Yanzhu because of the shift change, so Bao Shiyu fell into remorse. Before Yanzhu committed suicide, the school began to spread rumors that she was with Bao Shiyu, Youzhen (Wu Lianxu) and Enying (Min-jeong Song). Around them, classmates and friends around her began to talk about it and looked at them with strange eyes. The three of them were immediately shrouded in the shadow of the "declaration of death" on the eve.