Blue Exorcist - S05

Rin Okumura, unlike his twin brother Yukio, never cared to learn about their parents or the details of his own birth. But when Mephisto Pheles, the master of time, hands him a key that sends him 40 years into the past, Rin finds himself in the childhood of his late mother, Yuri Frederick Egin. Guided by Mephisto, Rin jumps through the years, observing Yuri as she grows up and trains to become an exorcist. During her youth, Yuri meets Shirou Fujimoto, the man who would later adopt Rin and Yukio. As Rin follows their lives, he sees the first encounters with Satan-his real father-and the dark events unfolding within the True Cross Order's secretive Section 13. Through Yuri’s strange bond with Satan, Rin uncovers the truth behind the Blue Night, the most terrible tragedy in exorcist history, and the night he and Yukio were born.