The Fake Karakura Town Lets the Captains Fight Without Sacrificing the Real One
SPOILER!Episodes 203 & 215 onward · Decisive Battle
Aizen needs Karakura Town for his larger plan, so Soul Society replaces the real town with a replica and moves the population out of the battlefield. That preparation turns the conflict into the series' largest captain-level war: Espada, lieutenants, Visored and captains collide while Aizen waits behind the force meant to stop him.