#blade.

          The slaughtering of Central 46 acted as Aizen’s way to promptly run the Gotei 13′s focus onto Rukia via illusion, deception, misinformation, etc. and in a similar fashion to Barragan’s army, the entire room filled with bodies were all slain nearly simultaneously. Now, we can chalk this up to Aizen being an off-screen badass, but I’d like to give Gin ( as well as Tousen ) the rightful recognition as the ones to have most likely killed them all. Considering none of the bodies were shown to have been able to even stand from their chairs, it’s reasonable to suggest that the attack happened swiftly with no room for any outbreak of panic. No alarms could be raised for any guards ( who were likely already killed by the traitorous trio upon entry, but still ) or any other failsafe raised in order to alert the Gotei 13 that Central 46 had fallen under attack. Despite how well-armed the fortress is described, none of those protective measures were able to be put into place.

          The lockdown? Happened after the inhabitants were slain.

          Tousen likely wished to engage the room by himself, feeling strongly about his justice for their inability to properly punish the murderer of his important person. Being a captain-class Shinigami, he easily could have slain all of the non-combative judges and elders without a sweat. However, due to Aizen’s desire to keep matters quiet, less so emotional, Gin likely was requested to help keep things clean ( much to Tousen’s annoyance ) and in control.

         This, of course, falls back to how quickly the slaughter occurred.

          In a circular room, filled, and stadium-seating style... how could everyone manage to die around the exact same time, sitting in their chairs ? This means no one visibly died first, delayed, gasping, as everyone else around them realized ‘oh, shit! we’re being attacked!’ no, it happened at the same time. Not a single member managed to crawl their way out of their seat, not even fall from it, and all of their blood-splatters are behind them, implying they were all struck ( or rather, impaled ) from the front------so I’m going to go ahead and say it:

        Gin killed the forty ‘wise men’ and left Tousen the six judges to seek his justice. He figured that was a fair trade rather than stealing the entire task from him.

          It’d be much easier to simultaneously strike down six men seated closer for Tousen’s particular ability, and far within Gin’s capabilities to kill dozens spread in a circle via Shinso’s specific skillset. They likely DID NOT EVEN SEE THE BLADE KILLING THEM considering even at Shikai-level speeds the weapon can shoot faster than a bullet. Gin is typically called upon by Aizen when dealing with striking down multiple enemies at once, as shown in his rescuing of Izuru, Hinamori, and Renji. He even had the reputation for that exact nature of his Zanpakuto as a child, so it’s not a stretch to say Gin handled the majority of Central 46′s demise. Gin went for the neck, impaling throats or skulls even, and aimed to end each life within blinks of one another. He didn’t particularly feel anything about the endeavor, though the slaughter was perhaps one of his highest kill-counts concerning people thus far. Up until then, it had been strictly Hollow, or failed Hollowfication projects in which their humanity was difficult to discern.