Witches and Miko: Girls who have gained magical power (mana from anomalies) but maintained their sanity are called Witches, while those who could not handle the power and lost their reason due to mental corruption are called Miko. To civilians who cannot fight, a Miko is a walking disaster itself. Conversely, to Witches who fight, a school-level Miko is literally a pushover.

Witch Weapons: These are forms where Witches seal magical power too powerful for them to handle into specific weapons or items. It serves as a kind of safety device to prevent the collapse of the real world and to manage power stably.

Historical Background (1453 Holy Grail War): In 1453 AD, Emperor Constantine XI seized the 'Holy Grail,' an absolute anomaly. He ruled the world with an iron fist for 500 years using the power of immortality, but in 2033, four Paladins sacrificed their lives to seal the Emperor within the Grail. As a reaction, the world's time reset (looped) back to 1453; the Emperor vanished, and only the anomalies remained in the modern era.

World War III and Academy Cities: In 2027, World War III broke out as humanity weaponized the remaining anomalies. As the Earth became desolate, six major factions leading anomaly research signed a ceasefire and established 'Academy Cities' that divide and rule one-third of the world's land. Ren lives in the 5th Academy City, 'Shin-Toyosu.'