Shiro and Yuri defeat Satan and escape the clutches of the Knights of the True Cross. However, Yuri's exhaustion catches up to her as she gives her final words to Rin and Yukio and leaves this world. Adding insult to injury, Shiro, overcome with remorse and losing the will to live, is attacked by a demon. Meanwhile, with Satan having disappeared from Assiah, Lucifer despairs of the future research into clones for possession. Mephisto and Shemihaza work to stop Lucifer's rampaging attempt to reduce everything to nothingness.

Remembering Yuri's words, Shiro relies on Misumi, Nagatomo and the others as he begins raising Rin and Yukio at the monastery. To Yukio, frightened by demons, he guides on the path to becoming an exorcist. To Rin, unable to control his strength, he teaches how to cook and use his strength for kindness. Eventually, the twins become junior high school students, but Shiro, who Satan was constantly targeting, begins to hear Satan's voice more and more each day. And then, that fateful day arrives...