Gigai

A Gigai, meaning faux body, is a crafted vessel that lets a Shinigami stay in the Human World and deal with its people face to face. Such shells have existed for at least a century, with Kisuke Urahara long known for tinkering with different builds. A Shinigami stripped of power often takes one, since only their abilities can carry them home to Soul Society, and dwelling in a Gigai lets them act human and avoid the Hollows that would otherwise hunt an exposed spirit.

Fresh from production, a Gigai wears the plain look of a generic, muscular figure with no distinguishing features, but once a Shinigami settles inside it reshapes to match that host and becomes visible to any ordinary human nearby. It does not conjure the occupant's clothing, so its user must find modern garments to blend in. Climbing back out can be awkward, and the quickest exit is to swallow a Gikongan, which shoves the soul free and installs a stand-in tasked with keeping the empty body safe.

Many variants exist for particular needs. Standard models simply house a Shinigami through long missions, while a reiatsu-concealing type once let Urahara, Tessai and the Visored vanish into the Human World undetected. His portable Gigai works as a battlefield decoy convincing enough to fool Aizen, and the Human Shell Gigai turns its occupant into a human-Shinigami hybrid able to live and even raise children as a person, at the cost of losing free movement and risking their powers. Most infamous is the first Gigai given to Rukia Kuchiki, so advanced that no researcher of the day could reproduce it, which quietly bled away her strength until she was nearly human while sealing the Hōgyoku deep inside.

Gigai are tools of the Shinigami as a whole, with Urahara standing out as their foremost designer. Rukia Kuchiki relied on the concealed model built to trap the Hōgyoku, and Isshin Kurosaki used a Human Shell Gigai that granted him a family in the living world. In the film Memories of Nobody, Senna carries a singular version she can leave at will, one that scatters into autumn leaves whenever she steps out of it.