During his time in high school, Yuuichi Katagiri highly values his tight-knit group of friends: Yutori Kokorogi, Shiho Sawaragi, Makoto Shibe, and Tenji Mikasa. However, everything changes when the funds for their school trip are stolen, causing Shiho and Makoto to distance themselves from the rest of the class. Before long, Yuuichi and his friends fall into a trap and lose consciousness. When they wake up, they find themselves in a sterile facility with the infamous Manabu-kun. Manabu-kun reveals that one of them arranged the meeting to clear a personal debt of 20 million yen. To succeed in the psychological tests that threaten their humanity and friendship, they must work together. Despite feeling disconnected and pushed beyond their limits, Yuuichi and his companions must collaborate to overcome the trials. However, their complex history and unspoken emotions could jeopardize the strong bond they've shared for so long.