|Name in Japanese||不可逆のネクローシス|
|Romaji Translation||Fukagyaku no Nekurōshisu|
|Release Date||July 20, 2011|
|Episode Director||Tomoko Hiramuki|
|Previous||Episode 15: Missing Link Necrosis|
|Next||Episode 17: Made in Complex|
Daru somehow manages to repair the time machine, and Suzuha learns the truth about her long lost father before traveling back to 1975 for one final, desperate attempt to change the future.
Okabe, along with Suzuha and Mayuri, meets up with the street vendor from earlier. The vendor tells him that a guy asked for a pin to be made, one that looked like the one Okabe showed him. When asked what the guy looked like, the vendor replies, “Like a barrel.”
With only a vague description, the team starts losing hope in finding Suzuha’s father. That is, until Okabe thinks up a plan involving the Time Leap Machine.
August 11th, 2010; 6:35 PM
Okabe time-leaps back in time to catch the ‘barrel-like’ guy meet with the street vendor. The guy turns out to be Daru. His plan was to have a fake pin made, show it to Suzuha, and fake being her Dad. As Okabe vents his displeasure over Daru's actions, he finds out that Suzuha’s time machine can only go backward in time; once she leaves, she cannot return.
Saddened by this revelation, Okabe later promises Suzuha that he’ll change the future into a free world, as it is in their present time.
August 13th, 2010; 3:07 PM
Back at the Radio Building, Daru finally manages to get the Time Machine up and running. After Okabe and Kurisu arrive with Suzuha’s cherished bicycle, Mayuri cleverly deduces that Suzuha’s father is actually Daru, a revelation that makes Suzuha cry tears of joy.
The Lab Members says their goodbyes as Suzuha leaves for the year 1975.
Later, as the Lab Members wait for the arrival of the IBN 5100, Mr. Braun comes to deliver a letter addressed to Okabe, from Suzuha. Mr. Braun tells them that she died ten years ago.
The letter, written in the year 2000, reveals that Suzuha failed her mission: after arriving to the year 1975, she had amnesia until a year before writing the letter. Apparently, the repairs to the Time Machine were incomplete, somehow causing the amnesia. She expresses her regret and anguish about forgetting her mission and living an easy life instead.
She requests, if Okabe could go back in time, that he not stop her from leaving the night that the storm damaged the Time Machine.
After reading the letter and learning that Suzuha died by suicide, Okabe decides to grant her wish and send a D-Mail to himself, to prevent him from stopping Suzuha the night of the storm. Despite Mayuri’s protests, he sends the D-Mail.
Okabe confronts Mr. Braun about the whereabouts of Suzuha; he learns that she still died ten years ago, but illness was the cause of death. She became Mr. Braun’s neighbor and later provided him a place to live after a fire burned down his home. He now lives in her old house.
Mr. Braun then brings out the Divergence Meter that Suzuha had, saying that the number it displayed was always on her mind until the very end. Okabe notices that the number went up, but not above 1%.
Later in the day, engulfed in thought over the things he’d learned from Mr. Braun, Okabe realizes that he isn’t with Mayuri, and that her time of death has arrived. He hurries to locate her, finally finding her at the Lab, still alive and sleeping.
He is brought to his knees in tears; in his mind, he asks Suzuha if Mayuri is now safe.