PIN

PIN (暗証番号, Anshō Bangō) is the twenty-first episode of the Future Diary anime it was released on 11th of March 2012

Summary
Yukiteru Amano takes hostages in an attempt to corner John Bacchus in Quad Towers. Meanwhile, Yuno Gasai saves Ouji Kosaka, Hinata Hino and Mao Nonosaka from Eleventh's custody.

The mayor hides out in a double-locked vault in a bank formerly owned by the Gasais, unlocked only by retinal-scanning Bacchus himself or a member of the Gasai family.

For allowing Masumi Nishijima to be killed, Minene Uryuu turns on First when his plans fall through. While Yukiteru hides from Ninth, she recounts her tragic past: orphaned in the Middle-East and having had to steal and swindle to survive.

Yuno attempts to take out Eighth, but is stopped by Aru Akise, and reads a message from her love that he is in danger. Uryuu briefly has the upper hand on Yukiteru, but she is shot when she hesitates upon seeing herself in the boy who just misses his parents.

Ninth offers a final sacrifice to Yukiteru's cause by detonating her dead-man's-switch bomb against the inner vault door and breaks her diary, at peace with her emotions and her feelings about Nishijima. However, the explosion fails to crack the vault. Yuno appears and sends First off to destroy the Holon III units. Despite his confidence that Yuno is an impostor and would not be able to open the vault, Second enters Bacchus' sanctuary and kills him.

In the following days, Akise gives Eighth shelter, despite believing Yukiteru to be the best candidate for Deus Ex Machina's successor. As he puzzles over Yuno's real identity, dark spheres begin to form around the planet, obliterating everything in their wake. Realizing that the destruction of the universe is imminent, Yukiteru becomes even more focused to end the survival game.

Kamado and Akise appear in Deus' realm, with the latter asking if it is truly possible for the game's winner to bring back the dead.

Muru Muru's Section
Muru Muru makes fun of the name Bacchus gives his Future Diary, getting on his nerves when she goes so far as to look at results on an open opinion forum on the subject.

Trivia

 * In the original Japanese version, Muru Muru calls Eleventh's diary the Old Man Diary (oji-chan), which is phonetically similar to the Japanese pronunciation of the English word "watcher" (uoccha), the actual name of his diary.
 * In the English dub, Muru Muru calls the diary the Peeper Diary, lending a perverse connotation to the surveillance/spying abilities of the Watcher Diary.