WARNING: The following contains spoilers for Episode 3 of Platinum End, "Heart's Beloved," now streaming on Crunchyroll and Funimation.
Mirai Kakehashi has found himself thrust into a heavenly but deadly battle royale, pitting him against twelve other God candidates in a contest where there can be only one winner. His brutal angel patron Nesse urges him to use the full extent of his powers, but Mirai dragged his feet until a chance meeting at school.
Mirai intends to keep his head low and pursue his humble happiness in life, but the angel Revel spots him at high school and confronts him. Revel's God candidate needs Mirai's protection, and Revel won't take no for an answer. Now Mirai is responsible for two lives, not just his own.
Mirai comes face to face with Revel, a male angel with gold eyes, then turns to meet Revel's God candidate -- Saki Hanagako, Mirai's crush. Saki pierces Mirai with a red arrow to win his loyalty with Cupid-like powers, unaware that Mirai already loves her. Saki invites Mirai to her home and explains that she only has the red arrows' power, so she needs protection.
Revel assigns Mirai as Saki's guardian angel, mostly to fly her around on his wings to outrun the white and red arrows of rival God candidates. Mirai agrees, and he takes Saki for a test flight. Even when Saki's red arrow expires after 33 days, Mirai's feelings remain unchanged toward Saki -- he admires her and will do anything to protect her. He has finally found the proper motivation to use his incredible gifts, which should satisfy Nesse.
This union complicates Mirai's position greatly, especially when taking the armored hero Metropoliman into consideration. Mirai now has two angels to fly around and scout for him and Saki, and Saki can lend him her ideas and insights in the heavenly battle royale. However, Saki has limited powers, and she cannot fly or kill anyone. Mirai must risk his life to protect her from their enemies -- and worse yet, an enemy such as Metropoliman could conceivably capture Saki or threaten her to pressure Mirai, thus becoming a liability.
This may remind Death Note fans of Light Yagami's and Misa Amane's team, where Misa quickly became a liability to Light despite having her own Shinigami, Rem, and the full power of the Shinigami eyes. Saki must take care to not weigh down this alliance and put Mirai at risk.
Mirai and Saki both recognize Metropoliman as their biggest threat, and they don't yet have a clear plan to take him down. Instead, Metropoliman appears on TV and invites all other God candidates to meet him at the Jinbo baseball stadium. Now Mirai and Saki face their first true challenge, and they demonstrate clear resolve and courage by going to the stadium despite the risks. Saki trusts Mirai to protect her, and they trust one another to spot any sign of danger and react to it before suffering any harm. Saki shows no sign of returning Mirai's amorous feelings for her so far -- she might just be using those feelings, making her a stone-cold manipulator for her own survival.
This new union also proves how aggressive Revel the angel can be. He wants more than Saki's protection -- he also wants Mirai to hunt down and kill a God candidate, then transfer that candidate's wings and/or white arrow powers to Saki. Failing that, Mirai could die in the process, and Saki could obtain his powers. Nesse shoots down this plan, and Revel gives up his little scheme. For Saki's sake, he might try another stunt in the future, and Mirai will have to watch out for that, too. Revel is as much Mirai's enemy as his friend so far.
