Location from Bleach by Tite Kubo
The hidden Quincy empire concealed within the shadows of Seireitei for a thousand years, ruled by Yhwach and staffed by the elite Sternritter.
The Wandenreich's existence is the series' greatest strategic reveal. For a thousand years, the Quincy survivors hid in the shadows of their enemies' own fortress, rebuilding their army while the Shinigami walked overhead oblivious. Yhwach founded it after his initial defeat by Yamamoto, spending centuries in a state between sleep and death, gradually regaining power. The Sternritter — his elite guard, each granted a Schrift letter-power — trained in this shadow dimension. When Yhwach finally struck, the Wandenreich didn't invade Seireitei — it replaced it, swapping dimensions in an instant. The entire Gotei 13 found themselves standing in enemy territory without having moved a step.
A mirror-dimension version of Seireitei rendered in blues and silvers instead of whites. Gothic architecture replaces Japanese — arched hallways, iron balconies, and the Quincy cross motif everywhere. The space exists in Seireitei's shadow, literally occupying the negative space between dimensions.
Also known as: Wandenreich, Invisible Empire