In volume 3 of the manga, Yuichi Katagiri says: "I know who the traitor is". He even claims to have figured out the strategy of the game. Mikasa looks at Yuuichi with a surprised face.
Yes, it was Mikasa who was the traitor. Due to the events of the past, Mikasa holds a strong grudge against Sawaragi and to bring her to ruin, he made her participate in the Tomodachi Game. He then tries to pass only Sawaragi to the next game. However, Mikasa shows a plan that surpasses Yuichi's intentions and pushes Sawaragi to the edge of the finish line, just as he intended. Just as he was about to fulfil his own wish, Katagiri made another move...
Now it is revealed that the traitor is Mikasa but only to the reader; the four still do not know who the traitor is. However, Yuichi Katagiri has been working on a series of schemes since the beginning of the crime fight and as a result has discovered that Mikasa is the traitor.
Yuichi corners Mikasa in front of everyone and tries to apologise in tears. However, there is not the usual kind face of Yuuichi , but one that looks like an evil man.
Tenji Mikasa , cornered both emotionally and circumstantially, has no escape and his betrayal is exposed in the light of day. However, the behind-the-scenes work that seemed to have been resolved has an unexpected ending. Katagiri confesses that he himself lied in his vote and tries to challenge the next party alone. He then declared that he would destroy the management of the Tomodachi Game.
Yuichi Katagiri's shocking past is also revealed. Can the four remain Yuichi's friends after learning about his past? This work becomes even more interesting as we delve into the pasts of Yuichi , Mikasa and Sawaragi , as well as other characters.
In addition, a surprising scene is shown in volume 4. It is a scene that shows that people who do not choose the means to an end are very problematic.