Yui's cousin, Courtney, gets sucked into the book. Ryo, a classmate of hers with a secret, saw it happen and sent Yui, Miaka, and later Tamahome, into the book after her.
A new God had sent seishi to the Earth after being locked up by Taiitscun. It was a loophole in his imprisonment. These seishi are so much stronger than the Susaku and Seiryuu seishi that the latter two enemies must team up in hopes of defeating them. Courtney becomes the Priestess of Shinigami (the new god) after being manipulated by the head Shinigami seishi, Maosi. She is destined to summon the God out of hi prison and be devoured by him before he unleases his fury on both the world in and outside the book.
Ryo, a new ally to the good guys, and a powerful one at that, has a duty to the book that he doesn't know of right away. He is destined to help in saving both worlds.
With the help of all inside and outside the book, perhaps the Shinigami may be defeated and the world will be saved...