Sakamoto enjoys a quiet life in retirement with his family. But one day, an old colleague demands he return to the assassin world — or face consequences.

While out on an errand, Sakamoto and Shin encounter Lu Shaotang, the daughter of a mafia boss, who's on the run and targeted by twin assassins.

After learning of the huge bounty on Sakamoto's head, the crew tries to enjoy a family outing at the amusement park while fending off assassins.

Sakamoto goes all out in a fierce one-on-one duel with Boiled. Meanwhile, ORDER members are tasked with handling a serial case targeting assassins.

To rescue Lu, Sakamoto and Shin infiltrate a top-secret lab seized by assassins. Meanwhile, in the prison cell, Lu meets someone from Shin's childhood.

In the depths of the Lab, Shin and Heisuke join forces to take down the invisible assailant, while Sakamoto engages in an intense battle against Kashima.