Episode 13: Metaphysics Necrosis#
Two days, on repeat. Okabe spends the episode inside a 48-hour loop trying to out-position fate with a phone, a bicycle, and a rapidly fraying mind — and the Divergence Meter is born from the wreckage.
Synopsis#
Leap one: Okabe warns nobody, moves Mayuri across town early. She dies at 19:51 — a traffic accident, streets away from any Rounder.
Leap two: he tells Kurisu everything. They hide Mayuri in Akihabara's crowds. 19:51 — a platform surge at the station. The pocket watch stops first, every time, like a courtesy.1
Leap three, four, five: the episode compresses further attempts into a montage that the fandom calls the necrosis reel, each loop shot with one fewer color until the frame is nearly gray. However the day is arranged, the Alpha field converges. Kurisu — briefed fresh each loop, believing him faster each time from the detail he carries — says the quiet part: the worldline has to change, not the day.
Between leaps, Daru and a hollowed-out Okabe begin assembling the one instrument that could prove it: a meter that reads the divergence number directly. Suzuha supplies the design — she has seen one before, she says, in 2036, built by a man she never met.
The meter's first assembled prototype displays $0.337187$ — on-screen confirmation of every reconstructed value this wiki's Alpha readings table lists for the arc so far.
| Episode | 13 |
| Japanese title | 形而下のネクローシス |
| Air date | 2010-06-29 |
| Arc | Raid arc |
| Worldline | Alpha $0.337187$ |
| Leaps shown | 5 |
| Mayuri's deaths | 5 |
| Built | Divergence Meter |
| Focus | Okabe |
| Previous | Dogma in Ergosphere |
| Next | Physically Necrosis |
| Leap | Strategy | Outcome at 19:51 | Divergence |
|---|---|---|---|
| 1 | Relocate early | Traffic accident | 0.337187 |
| 2 | Full disclosure to Kurisu | Station crowd surge | 0.337187 |
| 3 | Confront Moeka preemptively | Rounder response | 0.337187 |
| 4 | Leave the city by train | Derailment delay; 19:51 | 0.337187 |
| 5 | Do everything at once | 19:51 | 0.337187 |
graph LR; L[Leap -48h] --> D[19:51] --> L
Note the rightmost column: five radically different days, one unchanged worldline. The leap moves memory, not the line — exactly the limit Kurisu listed in her lecture. Escaping convergence requires raising $d$ past the anchor's tolerance, and the only lever that moves $d$ is undoing D-Mails.
Eight nixie tubes and a sensor no one fully understands — Suzuha's design, Daru's soldering, Mr. Braun's donated tubes.2 The Divergence Meter converts the arc's invisible arithmetic into a readable number, and its first reading is a sentence: $0.337187$, the floor of the field, the number at which Mayuri dies.
The escape threshold, per Suzuha's 2036 intelligence: $d \ge 1.000000$ — the Beta attractor field. No D-Mail the lab has sent moved the line more than $0.07$. They sent six.
- The undo arc is now fully specified: reverse the D-Mails of episode-10, episode-09, episode-08 — in reverse order, each one a person's wish taken back.
- The meter's 2036 original and its unnamed builder are resolved in the finale.
- Loop 3 gives Moeka her first post-raid characterization; her arc continues in episode-14.
Episodes 13–16 all carry "Necrosis" titles: the death is Okabe's Alpha-arc self. The man who leaps out of episode 16 is not the man who leapt into episode 13, and the show means the word clinically — tissue that will not grow back.
#lore #episode
Footnotes#
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Five loops, five stopped watches. The prop department built a rig so the second hand halts on camera without a cut. ↩
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Braun asks no questions. On rewatch — knowing what episode-14 reveals about his shop — this is the loudest scene he has. ↩