The books open with an unknown person asking Izaya Orihara whether he is capable of killing humans, considering how he loves them so much. He concludes that Izaya can only ever wave his knife around without any killing intent, and concludes that he is so cowardly and pathetic that it's hilarious.
Elsewhere, Setton enters the chatroom to see Taro Tanaka laughing by copy pasting "hahahaha"s. When told to look at the chat history to see why, Kanra uses his admin rights to delete the history. The topic moves onto Heiwajima Shizuo, until Saika joins the conversation and reveals herself present. As she is new to the internet and lacks self-confidence, she mostly only apologises before leaving for the night, as she is online at an internet cafe, so she could not stay there late. Celty then reminds the remaining online members to be aware of the increasing amount of gunned muggers in the streets of Ikebukuro, which Kanra then comments how Ikebukuro has never been safe, considering how the recently resolved Slasher case was dated to have occured back in the Edo Period. Once Celty leaves for a night job, Taro Tanaka and Kanra discusses Saika's relationship to the Slasher via PM Mode. While Taro Tanaka believes that Saika was probably a victim to the virus Slasher may have created, and therefore explains the weird messages from earlier, Kanra suggests the possibility that Saika is the Slasher. The proglogue ends with Kanra returning to the topic of Heiwajima Shizuo, and states that depending on the method, it is possible to kill him, and Taro Tanaka warns Kanra not to get DOLLARS involved.
- "Let me ask you, Orihara Izaya. Are you capable of killing people? Can you truly do it with your own two hands? Even if you wave around that knife of yours, it's still not to the point of death and there's never any killing intent. Well, in the end, you can only ever use people, isn't that right? You really are a despicable and cowardly guy, so much that it's laughable. Haha. Hahaha. HAHAHAHAHAHAHAHAHA."
- Conversation in the Chatroom between Kanra and Taro Tanaka
PM Mode《I only wanted to test if Saika knew how to make conversation. If you think about it, Saika is new to the internet and caught a virus, and that was why Saika left strange messages -- Setton also says the same thing.》 PM Mode【Well, it seems you're right.】 PM Mode《… Then, do you think those messages were connected to the Slasher?》 PM Mode【I think the Slasher was the one that created the virus.】 PM Mode【If that's the case, it would be normal to have a lot of different computers catch the virus.】 PM Mode【That's to show off it's power, and then spread the virus, right?】 PM Mode《Well, that's how it would normally go…. But there's still another way of looking at this--》 PM Mode《Saika is the Slasher》