Yoruichi Shihouin is the 22nd head of the Shihouin Clan, one of the Four Great Noble Families of Soul Society. She once served as captain of the 2nd Division of the Gotei 13 and commander of the Onmitsukidō, Soul Society's covert intelligence and operations corps, overseeing its elite assassins and spies.

From childhood, Yoruichi grew up alongside Kisuke Urahara and Tessai Tsukabishi at the Shihouin estate, forging a friendship that endured for years afterward. That friendship became a defining turning point in her life: when Kisuke Urahara was framed by Sōsuke Aizen for illegal hollowfication experiments actually carried out by Aizen himself on Shinji Hirako and several other Shinigami, Central 46 sentenced Urahara and Tessai to have their powers stripped and be exiled. Yoruichi, still serving as captain of the 2nd Division at the time, infiltrated in disguise and personally freed them from custody, then helped them and the newly-hollowfied Shinigami (later known as the Visored) escape to the Human World. Because of her involvement in the incident, Yoruichi lost her own position and standing in Soul Society, choosing exile alongside her friends rather than staying behind.

Following her exile, Yoruichi settled in the Human World, working alongside Kisuke Urahara and Tessai at the Urahara Shop, offering support from behind the scenes throughout the major conflicts involving Ichigo Kurosaki and his allies.

In terms of combat ability, Yoruichi is known as the "Goddess of Flash," a title earned through her mastery of Shunpo, making her one of the fastest Shinigami in Soul Society's history. She's also regarded as one of the greatest Hakuda (unarmed combat) masters to ever exist — so skilled that she almost entirely forgoes her own Zanpakutō, despite having achieved Bankai. Her Hakuda skill alone is enough to take down Espada-level opponents without drawing a weapon at all.

In addition, Yoruichi possesses the unique ability to transform into a black cat — a form she often uses to move discreetly, stay disguised, or simply enjoy her freedom without being recognized.