Akuma Island

Akuma Island is a remote island off the coast of the hi-tech city San Fransokyo in the animated film Big Hero 6 and the base of the supervillain Yokai.

Location
The island is nearby the bridge of San Fransokyo and a few miles away from the city.

Its name "Akuma Island" - "Akuma" (悪魔) being Japanese for "demon" or "devil" - could be a reference to Angel Island, a real island off the coast of San Francisco.

Characteristics
Its surface consists of various plants and rock formations. Despite the evacuation of humans from the area, the island is still teeming with life. A large portion of the island contains the laboratory of the now defunct Silent Sparrow project. The interior of the facility is a large test chamber for the portal. An observation deck adjacent to the portals is within the room where the tests can be monitored and controlled. Due to years of abandonment and wreckage, the facility is now worn down and dilapidated compared to its former pristine state. However, several parts of the equipment are still functional in providing remnants of the facility's past.

Lore
The island is now abandoned, but it was once the testing facility for Alistair Krei's teleportation technology. It's failure resulted in the forced shutdown of the project and the desertion of the island.

Since then, Robert Callaghan has been using it as a secret hideout after he faked his own death, salvaging what was left of the remaining teleporter and planning to enact his revenge on Krei.