WARNING: the following contains spoilers for Platinum End Episode 5, "Death Sentence," now streaming on Crunchyroll and Funimation.
The heavenly battle royale to decide the next God continues, and Metropoliman springs a deadly trap in the middle of the Jinbo baseball stadium as Mirai and his new ally Saki watch from the bleachers. They can't save the little girl from Metropoliman's wrath.
For a moment, Mirai and Saki feel helpless against Metropoliman and his elaborate schemes, but then a new ally approaches them, a God candidate named Nanato Mukaido, who offers to aid them unconditionally. He doesn't have long to live, and he vows to do some good in the world before his time comes.
Saki and Mirai welcome their new ally into Saki's room once Nesse the angel confirms he is telling the truth, and the man, Nanato Mukaido, explains himself. He was diagnosed with terminal cancer three months ago, and he had given up on life, leaving behind a young child and his pregnant wife. Then, an angel approached him and signed him up for the heavenly battle royale. Now, Nanato seeks to take down Metropoliman at any cost, since he can't bear the idea of his family living in a world where the thuggish Metropoliman is God. Mirai and Saki welcome Nanato to the team, but they correct him on a few points.
Mirai, who desires a quiet life of normal happiness, already learned that taking his own life will do no one any good. He urges Nanato to cherish his life and not give it up, mainly for his family's sake. Nanato agrees to live as long as possible and use that time to tilt the battle royale in Mirai and Saki's favor against Metropoliman. Nanato departs the meeting in better spirits than when he arrived, and it's clear that Mirai and Saki's heartfelt words got through to him. Nanato becomes Mirai's most powerful ally yet, and just in time.
One afternoon, Nanato joins Mirai and Saki for a strategy meeting, and he makes it clear once again how much thought he has put into this. Nanato, despite his gloomy attitude, has already worked hard to scope out all other God candidates and formulate the perfect plan. He reveals that he recently sent reporters, investigators, and psych experts to identify God candidates in Jinbo stadium during Metropoliman's battle there. He also took careful notes of each candidate's name, patron angel, and special abilities. This intel can support Mirai and Saki in their future endeavors against Metropoliman.
Nanato proves his worth with another lead and shares a photo of another God candidate with Mirai and Saki so they can investigate him. However, Metropoliman has already proven how resourceful and manipulative he can be. Mirai has his work cut out for him, and Nanato may not have a white arrow at his disposal. If not, Mirai may have to use force to confront Metropoliman in the near future, and Nanato can only do so much to help. Then there's the matter of "Girl A" on the news, who is evidently acting with newfound angel powers, likely given to her by Metropoliman himself. This is one more tense and bloody mystery for Nanato to unravel with Mirai and Saki during his last remaining days on Earth.