The Mole Song: Final

The Costa Firenze sails under an Italian flag, which means Japanese authorities have no jurisdiction to board and search the vessel. This international legal constraint forces Reiji to physically board the ship himself rather than simply waiting for a warrant that would never come.

When Masaya Hiura (Crazy Papillon) attempts to shoot Shuho, Reiji must stop him to ensure Shuho survives long enough for a lawful arrest. By revealing he has been Shuho's mole and ally all along, Reiji destabilizes Masaya and prevents him from killing the target, buying crucial time for the police operation.

Masaya Hiura, nicknamed Crazy Papillon, wages a personal vendetta against yakuza members involved in the drug trade. He attempts to eliminate Shuho as part of his crusade against drug-connected criminals, viewing the yakuza boss as a rival and enemy in his war on narcotics.

Junna Wakaki, Reiji's girlfriend, goes on a singles' cruise to temporarily put thoughts of their complicated relationship behind her. The mission timing forces Reiji to sacrifice his personal life, and Junna attempts to move forward by distancing herself from the uncertainty of his dangerous undercover work.

Leo, Shuho Todoroki's son, arrives at the Costa Firenze to finalize the transaction in place of his father. His involvement raises the stakes and forces Reiji to improvise, as dealing with the son rather than the senior yakuza boss creates additional complications for the arrest operation.

After the operation concludes, Junna receives a promotion that elevates her to a supervisory role over Reiji within the police force. This promotion reshapes their professional dynamic, creating a new power structure they must navigate as both partners and colleagues.

The shipment of 10 tons of amphetamines, disguised as pasta, is thwarted at sea aboard the Costa Firenze. The police successfully halt the drug pipeline and secure the evidence during Shuho's arrest, disrupting the yakuza's major narcotics operation.

Reiji accepts the undercover assignment because the police specifically designed the mission to derail his return to normal life and threaten his long-awaited marriage proposal. His duty as a police officer requires him to prioritize the high-stakes capture of Shuho over his personal plans, sacrificing his timeline with Junna for the operation.

Reiji physically makes his way onto the Costa Firenze despite the jurisdictional complications. Since Japanese police cannot legally search an Italian-flagged vessel, he must infiltrate the ship personally to get close enough to Shuho and execute the arrest at sea.

After Shuho is arrested, Masaya continues his vigilante crusade against drug-dealing yakuza members. His ongoing war on the drug trade persists even after the immediate operation ends, suggesting continued conflict between his methods and formal law enforcement.