Sakura Kinomoto was an ordinary 4th grader until the day she opened a strange book and let dozens of powerful magic cards loose on the world. Keroberos, the Guardian of the Clow Cards, informs Sakura that it is now her responsibility to find and capture the freed cards. However, much to the reluctant Sakura's dismay, things aren't going to be easy for her. Simply saying magic words and waving her wand around isn't good enough. Each card is a living, thinking, extremely powerful being. She'll have to learn to cope with her new responsibilities, as well as ordinary troubles involving love, school, family, and friends. With the support of her friend Tomoyo and a young boy with powers of his own, she must learn how to use her newly awakened magical abilities to collect each card and prevent the disaster that will befall the world if she doesn't.
Sotobamura is a small village with around 1300 residents; so small the village isn't even connected to a single highway. An isolated village in which old customs, such as the burial of the dead, are still practiced. One day, the bodies of three people are found dead. Although Ozaki Toshio, the village's lone doctor, feels uncertain, he treats the deaths as a normal occurrence. However, in the days following, the villagers start to die one after the other.
Yukiteru (Yuki) Amano is a loner who never really interacts with people and prefers writing a diary on his cell phone, with his only companion being an imaginary friend named Deus Ex Machina, the God of Time and Space. However, Yuki soon learns that Deus is not a figment of his imagination but real when Deus makes him a participant in a battle royale with eleven others. Within this "Diary Game", the contestants are given special diaries that can predict the future, with each diary having unique features that gives it both advantages and disadvantages.