This is the season that pulls the floor out from under you by refusing to fight anything. Mephisto hands Rin a door into the past and suddenly the show isn't about the twins at all, it's about Yuri Egin, a girl who talked to demons like they were people worth saving, and a young Shiro Fujimoto who smoked too much and swung first. You watch a love story you already know ends in fire, and it still wrecks you when the Blue Night arrives. The animation finally matches the material, and the writing spends its budget on faces and silences instead of flame effects. Go in expecting Rin cutting down demons and you'll be annoyed, because he and Yukio are mostly spectators to their own origin. Stay for the moment Shiro's whole grumpy dad energy suddenly makes complete, unbearable sense.

Rin Okumura's twin brother Yukio splits from him and heads to the Illuminati, searching for strength and answers. To stand against him, Rin concludes he has to learn why the two of them were born to Satan and a human woman, something he never wanted to know before. Guided by the untrustworthy Mephisto Pheles, Rin is sent roughly four decades back in time. There he follows his mother, Yuri Egin, from girlhood into her years as an exorcist in training, and sees her meet Shirou Fujimoto, the man who later raises the twins. Tracing their lives brings Rin closer to the truth of the Blue Night, the day he and Yukio were born.