The Great Archives (Daireishokairo) is a branch of Soul Society that is primarily a non-combative "division" that specializes in record-keeping. It is considered a separate branch from the other executive, judiciary and legislative aspects of Seireitei as a symbol of neutral history writing. Its members usually consisted of those unskilled in combat-related arts and kido, though it is not unknown for shinigami of the Great Archives to fight. The shinigami in charge of the Archives is known as the Headmaster, currently occupied by Ken'ichi Yamamoto.
Behind the scenes
The Great Archives was inspired by the movie Bleach: Memories of Nobody, specifically its primary motif being memories, though the Archives are mentioned and seen in the Bleach canon continuity. In order for the memories lost at the end of the movie to be regained, it would have to have been recorded and kept somewhere safe during the movie's events, which spawned the initial creation of the Great Archives.