Like many other shonen combat anime series, Bleach has simple, intuitive ranking systems and organization charts for its main characters and the factions they belong to. When protagonist Ichigo Kurosaki met Rukia Kuchiki in Bleach's first episode, he had no idea that a skilled warrior like Rukia was just a grunt Soul Reaper who takes orders from Lieutenants and Captains. Given the Gotei 13's age and importance, though, it's vital that these Soul Reapers have a rigid ranking system.
Source：https://www.cbr.com/bleach-ranking-system/
