Ao no Exorcist: Yosuga-hen EP4 - Satan Awakening

Nine years have passed. During that time, Shiro, Yuri, Rick and the others gained experience and grew up. Meanwhile, in Section 13, Elixir experiments continued. Although Amaimon successfully possesses a new body, Lucifer is still unable to find a suitable body, and in his suffering, his attachment to material things grows stronger. However, in the midst of this all, a being that is "the universe itself" incarnates in a certain test subject.