Yoruichi
Shihōin

Yoruichi Shihoin enters the story as a talking black cat with a deep male voice, and stays in that shape long enough that her transformation back, in front of a scandalized Ichigo, is one of the series' most famous gags. The cat is a disguise with a hundred years of history behind it: she was head of the Shihoin clan, captain of the 2nd Division, and commander of the Onmitsukido, and she threw all three titles away in one night to smuggle the framed Urahara out of Soul Society.

She is the best pure martial artist in the cast, the self-styled Flash Goddess, faster than her former student Soi Fon's assassination squad and strong enough to fight without ever drawing a sword. She drags Ichigo through his three-day Bankai training, carries the wounded out of collapsing battlefields, and delivers exposition with the smugness of someone who taught half the powerful people in the story.

In the Thousand-Year Blood War she and her little brother Yushiro join the Wahrwelt invasion, where she draws Askin Nakk Le Vaar, the Sternritter whose Deathdealing rewrites lethal doses. Their fight is speed against poison: Shunko lightning, the Raijin Senkei form, a thrown Heilig Pfeil caught out of the air and returned to his chest. The aired run leaves her mid-duel, carrying Yushiro clear and circling Askin, unbeaten and uncatchable.