Yukio breaks up with Rin and heads for the Illuminati. In order to confront Yukio, who seeks strength and the truth, Rin decides that she needs to know the secret of their birth, and with Mephisto's guidance, they embark on a journey to the past. Rin follows in the footsteps of her adoptive father, Fujimoto Shiro, and her biological mother, Yuri Egin, but the path they took in life is harsher than she could have imagined - why did a child be born between Satan, the god of demons, and a human? What was the "Blue Night"? What answer will Rin come up with when he finds out all this... The story finally reveals the core of "Blue Exorcist" -