The Key of Realms is a fabled intergalactic object with the power to open the space/time continuum. It was created along with the Four Dimensions as a means of accessing the latter, but few truly believe that these exist. It's existence was learned by Arika Gottama from M. Bison, who stated that the Four Dimensions are the remnants of the Street Fighter Universe, which was made inaccessible during a war which took its toll on the fabric of the Universe.
Made: During or after the Uni War
Purpose: To create a portal/gateway into the Four Dimensions