|Name in Japanese||無限連鎖のアポトーシス|
|Romaji Translation||Mugen Rensa no Apotōshisu|
|Release Date||August 10, 2011|
|Episode Director||Hiroyuki Tsuchiya|
|Previous||Episode 18: Fractal Androgynous|
|Next||Episode 20: Finalize Apoptosis|
The next D-Mail Okabe must erase will be the greatest challenge thus far in his quest to save Mayuri. Standing in the way of undoing the death he has witnessed so many times is none other than Moeka.
Moeka is seen standing on the edge of a windy roof, looking downwards and holding her phone. She purses her lips, and the screen zips away from her.
August 15, 2010: 8:03 PM
The lab members sit around, with Daru typing up things, Mayuri questioning how she should cook ramen, and Okabe and Kurisu sitting tensely by themselves. Mayuri invites Kurisu to a comic book convention, at which point Okabe solemnly recites all of Mayuri's plans, prompting Kurisu to take him to the roof. Okabe tells Kurisu there that, even though Mayuri has yet to die, he knows she will die eventually, and can do nothing but wait, and proceeds to re-tell her about everything at the park. He then notes that every D-mail undone pushes Mayuri's death back a day, and he plans to witness the death in order to make sure how much he needs to do to change the world line. He plans to undo Moeka's next, but he has to do it from her phone. Kurisu tells him to find Moeka while she tracks Mayuri, and tells him that no matter how many world lines he jumps, she'll always help him.
The next day, Okabe gets to work and has Kurisu report to him on them getting to the convention at Ariake. He finds where she works and contacts their offices, but learns that she only worked there for a day before not showing up. He then gets her address, but discovers that the police have shut it off. Okabe asks on the situation, but learns she committed suicide and begins to wonder if the Rounders killed her. As he prepares for another time leap, he hears from Kurisu at 7:52 PM that Mayuri died.
August 11th, 2010: 5:36 PM
Okabe time leaps and comes back to the moment when he has his pudding argument with Kurisu. He proceeds to call her by name, and tells her they have to save Moeka's life. He goes to her apartment alone, and finds the door unlocked. When he goes in, Okabe finds Moeka huddled in a corner with no lower body garments, quivering with her phone in hand and asking "FB" if she did something wrong because he won't give her orders. Okabe tells her they need to chat, but instead she begins fanatically typing "FB" into her phone over and over again. Frustrated, Okabe begins trying to wrestle the phone from her, breaking a table in the process. Okabe then realizes that the Moeka from the first world line started this when she killed Mayuri, and proceeds to punch a weeping Moeka and kick her against the wall before running out. He closes the door on her and leans on it to make sure Moeka doesn't get out, at which point Moeka begins screaming and pounding on the door. Refusing to listen, Okabe calls Kurisu and has her fire the microwave up, but when the D-mail is sent Okabe quickly realizes that he is still on the same world line as before.
He and Kurisu try to think why that isn't the case, and Okabe realizes that her phone is the same one that she had in the previous world lines, implying that her D-mail was not about getting a new phone. Moeka then proceeds to begin slamming her table against the door, and Okabe decides to learn what the message was by interrogating her. He opens the door and slams her on the ground, then proceeds to kiss her to avoid the woman next door noticing, only for Moeka to bite his lip and cause it to bleed. Conceding, she asks what she has to do to get it back, and Okabe asks about her D-mail. Moeka refuses to sell out "them", and reveals that her life is useless without FB, but Okabe says that can't be the case because FB doesn't even have a proper relationship with her. In a flashback, it is revealed that Moeka was once a lonely schoolgirl who was provoked to commit suicide by jumping off a roof, but at the last second she got a text from FB giving her a job. Okabe tells her that she commits suicide because she didn't get a text from him in a while, and that FB is just abandoning her the same way the world abandoned her before because he doesn't care. This causes Moeka to begin weeping and, after Okabe gets off her, huddling on the ground. Apologizing, Okabe begins looking through Moeka's texts, and asks FB's gender. Moeka admits that she doesn't know since they have never even spoken on the phone, but she is regardless devoted to FB because he/she made her feel like she belonged. Arguing that the lab tried to do the same, Okabe finds the message, which was to steal the IBN 5100 from the shrine. He and Kurisu prepare to send the D-mail that will undo it, but it doesn't work again. They can only conclude that Moeka didn't believe it, and Okabe realizes that Moeka will only obey the D-mail if FB tells her as such. He gives Moeka her phone back and tells her that he is going to locate FB. Moeka asks if she is really going to kill Mayuri, and admits that she will obey FB's order even if she knew that she was going to be sold out. Okabe says that, regardless, Moeka will commit suicide by fate, but that he decided long ago that he won't leave anything to fate anymore. He prepares to leave, but Moeka, deciding to believe Okabe, tells him where she hid the IBN 5100.