Saito is a security guard at Fantasien, a high-tech theme park where the central AI, MAOS, has begun to malfunction. After a day of minor mishaps and a near-fatal accident at the Ferris wheel, the park's whimsical atmosphere is shattered when a staff member is found dead. With MAOS issuing a cryptic warning, Saito is thrust into a deadly mystery.
As Fantasien faces corporate ruin and Hiromi Morimoto is arrested for murder, Tamami reveals her secret mission to avenge her sister's death. The situation escalates when the park's AI system, MAOS, suffers a catastrophic failure, trapping visitors in malfunctioning rides and turning the amusement park into a dangerous prison. Amidst the chaos, Takeshi and his allies struggle to stop a mysterious culprit who is manipulating the system to commit further crimes.
As visitors are evacuated from Fantasien, a rescue mission in the castle's basement turns deadly when the malfunctioning security system traps and kills several people. Amidst the horror, the truth behind Professor Kusakabe's death emerges, revealing a calculated plot of revenge and framing that manipulated Inoue into becoming a scapegoat for a deeper conspiracy involving the park's fatal system errors.