5x10 - Blue Exorcist

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.