Warning: Spoilers for Bleach: The Thousand-Year Blood War Episode 8The Soul Society in powerful Soul Reaper Captains and their well-trained followers. What few of these captains knew, however, was that there exists a secret Squad Zero, and their power puts every other squad to shame.
The structure of the Soul Society has long been an important element of Bleach. The 13 Court Guard Squads (sometimes also called the Gotei 13 by fans) exist with the permission of the Central 46, the governing body of the Soul Society, which in turn derive their power from the Soul King--essentially, God. Squad Zero aren't technically part of the 13 Court Guard Squads, but rather hold a special position as the Soul King's Royal Guard, and thus spend the majority of their time in the Soul King's palace.
Squad Zero's appearance is a bit ominous at first; while explaining to Ichigo how his Zanpakuto might be repaired, Mayuri Kurotsuchi receives a call telling him that the captains must assemble to meet Squad Zero when they arrive. They emerge from a rocket-like tower, with a mere five --except all five of them wield power on the level of a Soul Reaper Captain. Some of them seem to have relationships of some sort with living captains, such as the purple-haired Kirio Hikifune recognizing Shinji Hirako, while others appear to be complete unknowns. It's also stated that only the of Squad Zero are able to enter and exit the realm of the Soul King's palace because their very bones have been turned into Oken--a special key which Aizen had previously tried to create.
What's the Deal with Squad Zero?
As the Royal Guard, it's not their job to protect the Soul Society at large, so Squad Zero hasn't appeared yet in the series despite some of the enormous threats it has faced. Given the statement about their bones being Oken, it seems like the process of ing Squad Zero must be extremely difficult. And, while there may be another method, it is true that Aizen needed the reveal of Ichigo's Quincy heritage.
Bleach's Squad Zero may be powerful and technically on the same side, but their inscrutable motives for getting involved at this particular moment mean they still deserve to be viewed with some suspicion.
New episodes of Bleach: The Thousand-Year Blood War are currently streaming on Mondays via Hulu.
