The Imperial Palace, also known as the Castle, is a place located in the heart of Tokyo. It is heavily defended by the Four Gods outside the palace and guards all over inside. Genbu of the North, Seiryuu of the East, Byakko of the West and Suzaku of the South. These beasts have special abilities. It is also the home of the enigmatic Burst Linker, Azure Heir.
The palace itself is an anomaly. Brain Burst uses image data from the Social Camera to construct the battlefields. However, there are no such cameras in the palace itself. Thus, it should have been impossible for the interior of the palace to exist. Despite that, it did. This was further confirmed by Silver Crow, with the help of Metatron. He saw that there was really no cameras in the palace. It was also confirmed that the palace was also at center of Brain Burst's predesessor, Accel Assault 2038 and successor, Cosmos Corrupt 2040. Silver Crow and Metatron speculated the real goal of the game was to penetrate the palace and obtain the final arc, The Fluctuating Light.
- Accel World Light Novel Volume 16