Party's End is the 41st chapter Ajin: Demi-Human, created by Gamon Sakurai.
Tosaki attempts to contact Kei to report that the building has been locked down and the system has been destroyed but gets no response. Tosaki decides to try to meet up with Izumi but is stopped by a unknown phone call.
After successfully subduing Kei's group, Sato enters the empty presidents office and quickly realises that the room is slightly smaller than what was shown on the blueprint. Keiichi appears on the TV and gloats that he is safe in his panic room and that Sato won't be able to kill him. Sato tells him that he only has a knife and a gun and that it would take some time for him to kill Keiichi. Keiichi confidently tells him to do whatever what he wants.
Meanwhile, Kei is woken up by Hirasawa and notices Suzumura's and Manabe's bodies. He asks Hirasawa how long he was out and Hirasawa estimates that they were only out for a few minutes and that Sato has probably gone to the president's room. Kei asks Hirasawa to wake Nakano up and that they are going after Sato.
Back at the president's room, Keiichi is bragging about Sato's failure to kill him and that he should just go home. After hearing a gun shot, he looks over at the door and notices to his horror a hole. A moment later Sato's arm comes through the hole and successfully shoots Keiichi in the head. After successfully killing one of his targets, Sato wonders to himself where Naomi went.
After being revived by Tosaki, Izumi notices that the workers who had discovered her identity as an Ajin had been killed and their phones had been destroyed. Tosaki informs her that they are going to meet up with Kei but Izumi tells him that she is stuck. After looking at her wrist Tosaki tells her that he is going to find a key and starts heading downstairs. Izumi calls out to him but he doesn't respond.
Meanwhile, Naomi is wandering around the hallways on the 15th floor and is greeted by Tanaka. She closes her eyes accepting that she was about to die but to her surprise, Tanaka grabs wrist ordering her to come with him and to stay behind him. They are soon found by Sato who shoots Tanaka in the shoulder. Realising it was Tanaka, Sato begins to apologise but Tanaka stands in front of Naomi and points his gun towards Sato. Sato questions Tanaka's action and he tells him that he didn't believe that it was right to kill her. Sato accepts Tanaka's decision and tells him that he's dismissed but as he was walking away, Sato confesses to Tanaka that he was going to mess around with Kei a bit more.
Entering the president's room, Kei, Nakano and Hirasawa discover that Keiichi had been killed. Nakano questions how he was able to create the hole. Kei confesses to Nakano that they have failed and that the lockdown was a gamble and that since Sato was able to make that hole, trapping Sato inside the building was impossible.
A few moments later, Sato makes an announcement from the broadcasting room that his operation had ended and that Kei's was no good. He tells Kei that he was being too short and that he was wasting his potential. He tells Kei that he is going to decapitate him and once he does Kei will be able fight more creatively. He tries to encourage Kei before informing him that he was on his way. Sato goes to retrieve a landscaping tool and announces to himself that the bonus stage had begun.