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.