Gotei 13 (Thirteen Court Guard Squads)

The Thirteen Court Guard Squads, the Soul Society's army: thirteen captains, thirteen lieutenants and thousands of Soul Reapers who purify Hollows and guide souls.

Founded a thousand years ago by Genryūsai Yamamoto as an army of killers for the war against Yhwach, the Gotei 13 has grown into an orderly military body, led by the Captain-Commander and subject to Central 46's rulings. Becoming a captain requires Bankai and the approval of at least six captains, or — in the Eleventh — killing one's predecessor. In the series it faces the ryoka, the betrayal of three of its captains, Aizen's army and finally the Wandenreich.