"Irregular" is the 2nd episode of the anime.
The episode starts on May 23 at 10 PM with a flashback to the scene from the previous episode - Lin being ordered to kill Zenji Banba by Zhang. It is revealed Lin didn't actually agree to go through with this assignment but instead threatened Zhang that he'd kill any other killers Zhang sends to assassinate Banba until he pays what Lin thinks he owes him.
Lin is shown explaining to Banba that he will protect him from the other killers. Some time later, Lin falls asleep in Banba's office and Banba takes a photo of him.
Saitoh wakes up in a warehouse gagged and tied down to a chair. Jiro and Martinez are there. Martinez tortures another man to death in front of Saitoh for having tortured and killed a cat. Once he's done, Jiro removes Saitoh's gag to ask him about Murase's friends who were with him when he beat up the foreign men. Saitoh tells him he's not Murase and offers his Murder Inc. business card as proof.
Meanwhile, Shinohara, accompanied by Ivanov, blows up the car with Murase and his two friends inside, making it look like an accident.
Jiro lets Saitoh go and gives him his own business card. Yamato calls Jiro to ask him to avenge him getting punched by Lin the previous night.
In the morning, Banba tries to leave his office but Lin forbids him to. Banba sends Lin out to buy him mentaiko and once Lin leaves, he goes to the internet cafe where Enokida resides to ask about Lin's identity. It turns out Enokida has Lin's wallet, which Yamato stole, and has already looked up Lin's identity for the avengers.
Martinez corners Lin in the street and punches him to avenge Yamato. Then he leaves after giving Lin his business card.
Enokida asks Banba to give Lin his wallet back. Banba goes back to his office where Lin's waiting with a killer sent to assassinate Banba that he's caught. Banba asks Lin to let the killer go.
Zhang meets with Munakata to give him a young woman for Yusuke. The woman's unconscious and kept in a large suitcase. Instead of money, Zhang asks Munakata for Lin to be killed as payment.
Saitoh receives a call from his Murder Inc. boss who congratulates him on having killed Murase and informs him he transferred the payment to him. Saitoh calls Jiro to ask him if he killed Murase but gets to know that he didn't. Saitoh takes some of the money he's been paid and goes out to have fun.
Banba offers to pay Lin 5 million yen that Lin needs to pay back his debt for answering his questions and gets to know from Lin that Lin has been working for the Kakyuu Group and that the man in the photo with the mayor that Banba has is the Kakyuu Group's head, Longfang Wang.
Saitoh wakes up in bed with a dead woman and escapes in panic.
Lin takes the money and leaves Banba's office. He calls Zhang to let him know that he can now pay back his debt. Before the call ends, Lin finds out from TV news that his sister Qiaomei has been murdered. Zhang lets Lin know that he's sold Qiaomei to the man who killed her. Lin promises Zhang that he will kill both him and the man who murdered his sister.
- The man in the photo with the mayor taken at club Miroir whom Lin recognizes is Longfang Wang while it is Zhang in the light novel.