Rebirth (再生 Saisei?) is the 50th episode of Mobile Suit Gundam 00.
Plot
Setsuna accuses Ribbons of pretending to be God, but Ribbons claims that he is God. Ribbons believes that the human race will not stop fighting and will be destroyed unless he controls it, and he calls himself its savior. He compares what he’s doing to how people control animals, and he thinks that beating pure breed Setsuna cements his own value. In the ensuing battle, Setsuna is forced to evade while he waits for the Twin Drive system to charge, and when he tries to engage Ribbons at close range, he discovers that Ribbons’ Reborns Cannon is able to transform into a Gundam that has its own Twin Drive System. To make things even tougher, Ribbons gets backed up by Revive and Hiling, but fortunately for Setsuna, he gets his own help in the form of Lockon and Allelujah. With Hallelujah now as an active part of him, Allelujah/Arios goes up against Hiling and quickly tears apart her Garazzo, before transforming into flight mode to sever her suit's torso, killing her. The Arios, however, is subsequently disabled by Ribbons' GN Fangs. The Ptolemaios then arrives on the battlefield, and Ribbons attacks, damaging the port side engine. Sumeragi orders the release of a smoke screen despite it affecting Setsuna. This gives Setsuna the opportunity to attack, and with his Innovator powers active, he's actually able to do some damage to Ribbons’ Gundam. The Cherudim meanwhile is heavily damaged, but Lockon is able to make use of a one second Trans-Am to get the upper hand on and take out Revive with his spare GN Pistol.
Since the only opponent left is Ribbons’ Gundam, Sumeragi orders Ian to prepare to launch the R2 despite them not having a spare GN Drive. Ribbons meanwhile attributes Setsuna’s power to him having an original GN Drive, and Ribbons wants it back because otherwise his own creation would be meaningless. Tieria, however, uses Veda to tell Ribbons that their mission was not to lead mankind but to create a future with it, and he points to how Ribbons looks down on mankind as the reason why they can’t understand each other. Ribbons and Setsuna then engage their respective Trans-Am Systems, and although Ribbons scores several hits, Setsuna quantizes and manages to get a critical slash in. Unfortunately for Setsuna, Ribbons counterattacks and is able to slice off one of the 00 Raiser’s arms along with a GN Drive. This allows him to steal the GN Drives, but he finds that the Reborns Gundam has suffered too much damage to continue on. By chance, he happens upon the abandoned 0 Gundam, drifting out of one of Celestial Being's hangers and decides to stick the 00 Raiser’s GN Drive into it (Which was the GN Drive of Gundam Exia). When he returns to where the 00 Raiser is to finish Setsuna off, he discovers that Setsuna is gone and so was the right GN Drive. As it turns out, Setsuna has returned to the repaired Exia, now GN-001REII Gundam Exia Repair II and has reinstalled its GN Drive (which, coincidentally, was 0 Gundam's original drive).
The two continue their fight on Celestial Being's surface, and it ends with them charging at each other. Both pierce their weapons into the other’s Gundam, and it results in the 0 Gundam exploding. With the Exia having taken significant damage as well, Setsuna is knocked unconscious, as the flower Feldt gave him flies out the cockpit through the big gaping hole made by 0 Gundam and soars off to Earth. Sometime later, Marina writes a letter to Setsuna to tell him her feelings. She knows that as a child soldier, he was coerced to fight and was only able to live on the battlefield. The two of them have the same desire for peace and understood each other, but Marina questions why their paths didn’t cross. She goes on to wonder about Setsuna’s own happiness even as he tries to get rid of strife in the world, and she believes that sharing one’s happiness with others and expanding that circle leads to true peace. That’s why she wants him to get a grip on his own happiness, and she’s praying that happiness comes to him. Marina then gives a speech to a large crowd touting how Azadistan was able to rebuild with the Earth Federation government’s aid, and she promises to work hard so that all countries of the Middle East get this aid. To herself and Setsuna, she promises to expand this small peace.
Elsewhere in the world, Saji is thinking to himself about how the progression of Louise’s cell disorder has been completely stopped. He wonders if it’s thanks to the light that Setsuna released, but even if he doesn’t understand it, he knows that Louise is with him now. Louise is at this moment watching the new Federation president give a speech about A-Laws being disbanded and about the Federation army being reorganized. The new president also vows to support non-Federation countries and to promote Federation participation to establish a true Earth Sphere Federation. Shirin and Klaus are part of the audience, and they feel that the world is just now starting to change. Klaus realizes that it’s easy to talk about understanding each other and a world of peace, but they have to aim for it for the sake of the children to come. Back at the hospital, Louise wonders what will happen to the world now, and although Saji isn’t sure, what he does know is that they can’t be unaware of everything. They know the importance of peace because they also know the reality and the battles, and they need to think about the world if they really want peace.
On her wedding day, Kati gets a call from Andrei asking about Celestial Being. Kati honors them for helping beat A-Laws, but she feels that as long as they don’t disarm, they’re seen as a threat to the current government. If Celestial Being makes a move, Kati - who’s been promoted to the rank of brigadier general - is ready to move as well. But on this particular day, what’s important is that she’s getting married to Patrick. Andrei meanwhile has been put in charge of a relief operation, and he vows to live as a soldier like his parents, protect the citizens, and fight against those who threaten peace. Billy goes back to his research, accompanied only by a photo of himself and Sumeragi, and he is visited sometimes by Graham. His uncle Homer has killed himself, rather than face the consequences of massacre. Of the Gundam pilots, Lyle takes some time off to visit the graves of his family and Anew to tell them that he’s left Katharon and will live as the Gundam Meister Lockon Stratos. He feels that even if he’s shunned from the world, he’ll continue fighting, and he wants Anew to wait for him in the afterlife. Allelujah and Marie, on the other hand, have left Celestial Being to begin a journey to find the meaning of their existence. Tieria is still part of Veda, and he’s entrusted the future to mankind and will watch over them until the upcoming dialogue.
Reflecting on everything, Saji thinks that no one knows what will happen to the world, but he feels that whatever happens, happens. They can change the future and move towards the world that they want, and if they make a mistake, Saji is sure that Celestial Being will be there. At that moment, Setsuna is on board the Ptolemaios with Sumeragi, Lockon, and the rest of the crew, and he feels that they still have something to do. As the Ptolemaios launches toward space, Setsuna thinks about how they are Celestial Being, the ones who are aiming for the eradication of war. Even if the world abandons them, they’ll continue to face off against the world, and even if they themselves have to use force, they’ll live as a deterrent. For the sake of the future, Setsuna feels that they have to continue to exist.