"Play Ball" is the 1st episode of the anime.
The next scene takes place eighteen hours earlier. Lin arrives to an apartment, looking for a man named Takashi, and tricks the man's lover to let him inside. Once she lets Lin in, he kills her before cornering Takashi. Takashi attempts to persuade Lin to let him go by offering him money, but Lin declines and kills him. After finishing the job, Lin walks around the city when he receives a call from his employer Zhang, who asks him to kill a police detective that was looking into their organization.
Meanwhile in the Tokyo office of Murder Inc., Saitoh says goodbye to his coworker Nguyen before being transferred to the Fukuoka branch.
Back in Hakata, Lin goes to detective Takeda's address to kill him but learns that Takeda already committed suicide. He calls his employer to inform him of the news, trying to still take credit for the kill.
Banba and Shigematsu meet in Kego park to discuss the detective's recent death. Shigematsu shows Banba a photo of the detective's body and tells Banba that the detective was investigating organized crime, which the two deduce that the detective must have been strangled and was made to look like a suicide. Shigematsu then provides Banba with a photo of Mayor Harada, a woman and tow men at Club Miroir, whom detective Takeda had been investigating into. The mayor and the same woman from the photo are present at the park. Banba buys a balloon and stealthily pops it to create a sound resembling a gunshot to watch their reactions, noticing the stance the woman took indicated she was a killer.
Later, the woman, Reiko, gets into a car with her associates Munakata and Shinohara. Munakata informs her that another one of the mayor's hired killers, Ivanov, killed the detective, making it look like suicide. Munakata receives a call from the mayor's son, Yusuke, who asks him to take care of the body of a woman he killed.
Banba meets with Enokida at an internet cafe and tasks him to find out Reiko's identity. He also learns about Ivanov, a killer who left Murder Inc. at the same time as Reiko and specializes in strangulation.
Ivanov, Reiko and Shinohara go to Yusuke's place. Ivanov and Shinohara take away the dead woman's body in a large suitcase while Reiko tries to reprimand Yusuke for his actions, except Yusuke easily brushes her off. Yusuke begins to watch a video he took of his friends whom he had ordered to beat up college kids for fun. Seeing that, Reiko calls Munakata to inform him of another problem they have to clean up.
Elsewhere, one of the men who were beaten up by Yusuke's friends goes to Bar Babylon, seeking assistance from the avenger, Jiro. The man gives Jiro a card he took from one of his attackers - Jun Murase - and asks Jiro to avenge his friend. At about the same time, Saitoh gets the assignment to assassinate Jun Murase when he arrives at the Fukuoka branch of Murder Inc. Saitoh's boss gives him new business cards for him to use with the fake name Takuya Itou on them and warns him about the infamous killer of killers, the Niwaka Samurai.
Later at night, Banba bumps into Yamato on the street, catching him from stealing his wallet. They go to Genzo's food stall together where Banba asks Yamato about the photo of the mayor. Yamato recognizes Takashi as one of the men in the photo and informs Banba that Takashi was killed this morning. Once Yamato finishes his meal, he leaves where he encounters Lin arguing with Zhang on the phone over payment. He walks over and bumps into Lin, successfully stealing his wallet but enrages Lin and gets punched in the stomach. Lin storms away, but Yamato pulls out his wallet and swears to get revenge, planning to call Jiro to do so. Meanwhile, Banba heads to club Miroir and questions the boss about the man in the photo who was with the mayor. The worker claims to not remember those clients, and Banba heads home.
Saitoh goes out to buy supplies to carryout the assassination task given to him before heading to Jun Murase's apartment. While he waits for Murase to come home, hiding in the bathroom, someone rings the door bell. Saitoh goes to see who it is, and sees Jiro and Misaki there. He opens the door to talk to them, pretending to be Murase, unaware that these two were also after the same man he was. Jiro knocks the wind out of Saitoh and with Misaki's assistance they bind him and kidnap him.
Lin arrives at Zhang's office and confronts him about not getting paid for Takeda's death. Zhang refuses to pay him, as the kill was not his, before tossing him Banba's business card and ordering to kill him. Elsewhere, Munakata informs the mayor about his son's behavior, but his employer orders Munakata to buy women from a human trafficker for Yusuke to keep him appeased.
The final scene comes full circle with the beginning of the episode with Banba finding Lin in his apartment. When he hears Lin say he was sent to kill him, Banba grabs a stick and attacks Lin. Lin blocks it with his shoe and questions why he attacked him, telling him he came to protect Banba instead of killing him.