Episode 25

Stop, Time (時よ止まれ) is the 25th episode of the Ao no Exorcist anime overall and of the first season. It is also the final episode of the first season. It first aired on October 2, 2011.

Synopsis
Rin, Yukio, Shura and Arthur join forces to bring down the Gehenna Gate with no success. Meanwhile, Demons keep coming through it and giving a hard time to the other Exorcists until the Exwires come with a plan to open a gate to the Vatican, where it is already daytime, and reflect the sunlight there to the Academy where it is nighttime to weaken the monsters protecting the Gehenna Gate. Rin and Yukio manage to seize these opportunity and when both unlock their Demonic powers together, they fly through the gate and destroy it.

Satan appears as a small blue flame in a dark void, where Yuri's voice greets him. He apologizes for failing to fulfill his promise. However, she doesnt hold it against him; instead, she tells him that they both tried to make the new world too fast. It has to happen in steps, just like their sons.

Observing the aftermath from the fight, Mephisto tells Amaimon that this incident has reminded him of a bet he made once in the past; he gave an elderly scholar immortality at the cost of claiming his soul when he wished to die. As he expected from the beginning, Mesphito won the bet but had always been puzzled by the man's dying words "Stop, time. Thou art so beautiful." Mesphito tells Amaimon he now understands how that old man felt in his dying moment; he didnt desire to see all of eternity, but wished to live in that one moment forever.

One month later, things return to normal at the Academy and the Okumura twins return to the cave where they were given birth and pay a visit to their mother's grave.

After visiting their mother's grave, they meet an "evil spirit" in a highway. Rin appears from a highway cave with Kuro. The evil spirit then attacks Rin and Yukio. Rin destroys the evil spirit's first body and then the spirit takes control over a truck. Yukio shoots at the truck, Rin tell hims that there is somebody in the truck. Yukio says its just a dead corpse, but Rin believes the driver is still alive and that it's an Exorcist's job to protect people and defend against Demons. He tells Yukio and Shura to find its weak point and charges after the monster.

Trivia

 * Its implied Satan actually died in this version of the story as he meets Yuri's spirit.

Manga & Anime Differences
This is an anime only episode, it does not appear in the manga.