Keys play an important role in the world of Blue Exorcist. Magic keys allowing for instantaneous transport between two points are a staple tool of the True Cross Order and very valuable, requiring Exorcists to take good care of them. Despite their versatile ability, there is a limit to the use of the keys, being unable to transport even as few as six people over a significant distance. Other types of magic key exist, but they do not appear to be as prevalent.
Cram School Key
Key of Eternity
Key of Vanishment
Kyoto Branch Office Key
A key that allows direct access to the Kyoto Branch Office of the True Cross Order.
Labyrinth Garden Key
Supply Store Key
A key that allows access to the Exorcist Supply Store located in True Cross Academy. It is only given to fully qualified exorcists and access to the store is also restricted to them.
Tsukumo Kamiki's Key
This key is linked to Tsukumo Kamiki. A get-well present for Izumo Kamiki from Nemu Takara's employer, it opened a door to the adoptive home of her younger sister. It is unclear if the key only links to this location, or it specifically follows where Tsukumo is at the time.
Yuri Egin's Key
A key that only appears in the anime. It was kept by Mephisto Pheles, linking to the mountain cottage owned by Yuri Egin. It is eventually passed on to Rin and Yukio so that they can visit the place where they were born.
- Tsukumo Kamiki's key seems to be designed aesthetically for her, having a crescent moon for the handle and her name containing the kanji for the same.