Saito, a rookie at a contract killing company, has been demoted to a post in Hakata, a highly competitive market for hitmen. Banba, a private investigator, is asked to look into a detective's apparent suicide.
Hayashi had seemingly snuck into Banba's office to kill him, but instead intends to protect Banba in order to get back at his employer, Zhang. Meanwhile, Saito narrowly avoids being tortured and killed due to a case of mistaken identity.
Saito has been blamed for a murder he did not commit and hires Jiro to get revenge on the real murderer. Meanwhile, Lin learns that his sister was killed in Hakata and confronts the killer's employer.
Working with Enokida the information broker, Lin establishes that his sister's killer is the Mayor's son Yusuke. Having obtained information about the next human trafficking deal, Banba and Lin form a plan.
The Yamagasa Festival, one of the biggest festivals of Hakata, is in full swing and Banba is taking time off work to celebrate. Meanwhile, the ace assassin Saruwatari has become bored with his work and decides to move to Hakata.
Saruwatari craves a strong opponent and someone proposes going after the best assassin in Fukuoka, the Niwaka Samurai. Lin pretends to be the Niwaka Samurai and goes to kill Saruwatari, but quickly gets into trouble.
Targeted by a hacker hunter, Enokida is forced to run from place to place in Hakata. Assassins after the bounty on his head are steadily closing in, and Enokida has been cut off from using computers, his only weapon.
After a life of cruel wandering, Lin has found a place to be. The good-natured Banba has invited him to join his team of private investigators as well as his baseball team, the Hakata Tonkotsu Ramens.
Banba and Lin have decided to clean out the Kakyu Association executives from Fukuoka. Meanwhile, Nitta is negotiating with an organization vying to gain a foothold in Japan.
Employed by the Kakyu Association, Fei-Lan begins to seek revenge on assassins. His first target, Saruwatari holds his own in a fair fight, but is taken by surprise. Meanwhile, Lin has run away from Banba and is hiding in Enokida's internet cafe.
Lin goes to see Fei-Lan, but fails to convince him to stop. Banba arrives to help, but they are both captured and Fei-Lan orders them to fight to the death. Facing the same choice from his past, Lin must choose between killing and being killed.