Tsumugi Shirogane and Kaede Akamatsu started dating long before the killing game. Shirogane shared her thoughts, ideas about it with her girlfriend, who was excited and waiting for the moment to participate there with Tsumugi.

And that moment came, all of their classmates, them included, were changed into different clothes and listening to a black and white, teddy bear telling the rules. When he finished speaking, just as suddenly as he had appeared, he disappeared from sight. Their classmates were frightened, but only two girls wanted this game. When everyone had gotten to know each other, they dispersed to different places, trying to make sense of what had happened.

The two girls were in Tsumuga's room, lying on the bed, cuddling and thinking about who to kill and who to frame. They found it very amusing, and wanted to see their pain and despair afterward.

Suddenly, Shirogane said, frowning. "..Don't you think that shy detective would immediately guess who the real killer is? I don't like him". She gently went through her girlfriend's hair: "Hmm...Or maybe I'm just winding myself up. Either way, we need to be careful and make sure we have an alibi." Tsumugi smirked as she said. "Imagine if they all die and only we survive, that would be wonderful. Just you and me".