|Name in Japanese||形而上のネクローシス|
|Romaji Translation||Keijijō no Nekurōshisu|
|Release Date||June 29, 2011|
|Episode Director||Hisato Shimoda|
|Previous||Episode 12: Dogma in Ergosphere|
|Next||Episode 14: Physically Necrosis|
Okabe, desperate to prevent the tragedy he's already seen happen, summons the courage for a daring Time Leap. Can he save the life of his oldest and dearest companion?
Moeka Kiryu, accompanied by 5 men with guns, declares that SERN is confiscating the Lab's time machine, as well as taking Okabe, Kurisu, and Daru into custody. When Okabe asks about Mayuri's welfare, Moeka says she is “unnecessary.” Moeka shoots Mayuri in the head.
Okabe, now in shock, gazes at Mayuri's lifeless body on the floor. He goes to hold her, yelling her name.
While in shock and disbelief, Moeka appears behind him, pointing a gun to his head.
Suddenly, Suzuha runs into the room and bare-handedly incapacitates the 5 gun-toting men. She picks up a gun that one of the men dropped and points it towards Moeka, with Moeka pointing her gun at Suzuna's head.
While in the stalemate, Suzuha tells the remaining Lab members—in broken phrases—that the big TV downstairs (the “lifter” for the Phone Microwave/Time Leap Machine) is on.
Suzuha creates a distraction, allowing Kurisu to start up the Time Leap Machine. Okabe insists to be the one who time-leaps, despite Kurisu's doubts. The leaping process begins, just as Kurisu is shot in the back.
We then see a flashback of Okabe and Mayuri at a cemetery. Okabe explains that Mayuri's grandmother died when she was younger, and that she visited her grandmother's grave for months afterward. She would look up at the sky, as if she was waiting for her grandmother to come for her.
Then, one day at the grave, rays of sunlight surrounded Mayuri, as if she was about to vanish. Before this can happen, Okabe runs to her and hugs her tightly. He tells her, for the first time, that she is his hostage, and that she can't leave.
- August 13th, 2010; '4':'56' PM
Okabe finds himself in the Lab with Kurisu and Daru. Finding out that it is nearly 5:00 PM, he realizes that the time-leap worked. After telling the other two that the “development conference” is canceled, he leaves to find Mayuri.
Okabe checks different places where she might be, including Urushibara Shrine and the Ramen Shop. At the former location, Ruka tells him that Mayuri was with her thirty minutes ago and left to go to the Lab. Okabe tries calling her (as well as Faris), be she doesn't answer her phone. Okabe then runs into Suzuha, who tells him where Mayuri is.
Finally, after so much running around, Okabe finds Mayuri in an alley, looking at a star in the sky.
Okabe leads her to a nearby train station. When Mayuri notices that no one is on the train platforms, Okabe remembers that, before he time-leapt, a bomb threat shutdown the trains.
Just as the two of them prepare to leave, a man covertly points a gun to Okabe's back and tires to apprehend him. However, Okabe and Mayuri are able to get away.
As they continue to run from even more men, Okabe is broadsided by one of them. He tells Mayuri to keep running, but just then, a car appears, and fatally hits her.
Shocked and angry, Okabe breaks free and runs to the Lab. Once there, he initiates another time-leap, swearing that he will save Mayuri.
- August 13th, 2010; '4':'17' PM
Okabe makes up a story to convince Kurisu and Daru to leave the Lab; he then goes looking for Mayuri. By calling Ruka and getting him to keep Mayuri at the shrine, Okabe is able to locate her.
The two make their way to the subway, while simultaneously evading suspicious men all around the city. Once at the subway, they wait for the next train to come.
After mentioning that her pocket watch has stopped, Mayuri tells Okabe that she has a lots of questions, but she will ask them later. Okabe promises that he'll explain everything in time. They both wish to have that party with everyone sometime in the future.
Just then, as the next train is about to pull up to the station, Mayuri is pushed into its path. The train stops. All are in shock, including Okabe, as well as the person who pushed Mayuri: Nae, who only wanted to surprise her.
Okabe, picking up Mayuri's dropped pocket watch, vows to save Mayuri.
He then proceeds, once again, to time-leap.