Yuuichi Katagiri has endured financial hardship throughout his life, yet he has managed to remain content and positive thanks to his close circle of friends. To fulfill a promise made to them, Yuuichi saves enough money to join the group on a school trip. However, when the collected funds mysteriously disappear, suspicion falls on two of Yuuichi's friends: Shiho Sawaragi and Makoto Shibe, who were responsible for collecting the payments. Although innocent, Shiho and Makoto accept responsibility for failing to safeguard the money when no one else comes forward. A few days later, Yuuichi and his friends receive mysterious letters that trick each of them into meeting up. Upon arrival, they are ambushed and knocked unconscious. They awaken in a mysterious room in the presence of "Manabu-kun," a character from a controversial children's show that was cancelled due to its malicious content. He informs the group that one of them indirectly brought them together to settle a large debt. They are forced to play a "friendship game": a series of challenges designed to test the strength of their bond and trust in one another. As the group's faith wavers due to the growing number of secrets and betrayals, Yuuichi must determine which of his "friends" he can actually trust and ultimately uncover the identity of the traitor.