zanpakutO  

Hideyori's blade is an ōdachi, sheathed within the deep purple color associated with the First Division. The blade is scarcely decorated: there is a yellow tassel at the end of the blade's hilt, and a ridged blue texture on the handle itself.

When using his Zanpakuto to fight, Hideyori utilizes a devastating iaijutsu-style that delivers swift, quick blows in succession. Hideyori re-sheathes his blade after every combination of strikes, which makes it difficult to track or predict his next movements with the blade. Confounding his foes with speedy unpredictable movements is how he is able to make up for his average level physical strength.

zanpakuto spirit

Sankeihana's spirit manifests as a samurai in kamishimo. He is pale and appears quite famished in spite of his tall, elegant stature. Growing over his skin are budding flowers from the spores he produces. Cascading over his shoulders and down his back are unkempt, dark curls. Narrowed eyes gleam at others with a pair of menacing red hues... Most would argue he appears as though he were a vengeful yūrei. His mannerisms with Hideyori are overly familiar and he is very protective of him. However, he is often trying to entice Hideyori to be the worst possible version of himself, to "give up pretending to be a good person." His cruel and selfish advice is only meant to serve in their own best interests, to help Hideyori avoid the pain of betrayal and isolation.

Hideyori's inner world resembles the courtyard garden of the Tatsuda manor in his living life. The garden is flush with life except for where Sankeihana sits and awaits his master, surrounded by decomposing plants.

shikai

When Hideyori's release command "Obey, Sankeihana" is said, his blade becomes a parasol constructed out of plant matter. The staff is made out of hollow segmented bamboo, and a thin concealed blade lies in wait for enemies that get too close. The umbrella itself is flush full of life: green foliage is decorated with blue and pink flowers that emit a sweet scent. Underneath all this deceptive beauty however are fungal spores that are released in a radius around Hideyori, with its aim to infect other beings: enemy or ally. Just as with regular spores, wind and movement can help spread them farther.

Once the fungal spores make contact, they target the nervous system and will begin to seize control of the foe's muscles, appearing to paralyze the foe. Thus, many wrongly assume the nature of Hideyori's Shikai ability is merely a paralyzing gimmick, something more along the lines of a toxin than an assault and complete takeover of the nervous system. 

The embedded spores can also lie dormant in a target and activate upon command. If this is the case, one will find a single fungal flower growing somewhere within their inner world. This is the only indication that one has been infected with a dormant spore.

Active spores will feed on the host's Spiritual Energy until it is able to reach maturation. Upon doing so, a stem will sprout from where the spore(s) entered the host's body and begin to bud. A flower will bloom and then release more spores, which will continuously infect others in the vicinity.

bankai

When Hideyori is ready to use his Bankai, he will hold out his open parasol vertically before him. Upon the release command, Sankeikajoki (散形花序気, "Umbel Mind"), the stem of the parasol will extend downwards into the ground, then the umbrella will shoot high up into the sky and expand outwards, enveloping the entire area (about 50 meters outwards from the stalk) under its shade. This drastically increases the rate of spore infection, as the spores will rain down in the entire area.

The spores will not only affect "living" souls, but also the surrounding area, turning the entire section of land underneath the parasol into a "spirit garden"—one that resembles the garden of Hideyori's inner world. The land will become flush with greenery, as well as the blue and pink flowers present on the Shikai release. This means that the Reishi of the entire area is being absorbed for the fungus' upkeep.

As for those who are infected with the spores, Hideyori will now be able to control their bodies through their nervous system. This is a complete control over any sensory functions: Hideyori can make the infected do almost any physical task required of them. This control is very difficult to fight against, so it is a race against time for the host(s) to prevent multiple spores from seeding and taking root.

Caveats include:

❀ The higher the Reishi level of the area, the longer the Bankai can be used. Meaning, areas like Hueco Mundo and Soul Society increase Sankeikajoki's power, but the Living World weakens it.

❀ Since the stalk of the parasol becomes embedded into the ground, Hideyori loses access to his concealed blade and essentially becomes weaponless. He will have to rely on Kido or the infected for self-defense.

❀ The more spores, the stronger the hold he has on another. The less spores, the easier it is to fight against the control. That being said, this is also dependent on Reiatsu level. Those with less Reiatsu will require less spores to control.

❀ Some abilities provide a natural immunity against Sankeihana's spore infection. For example, Yumeshiro Hatada's Reiatsu and Zanpakuto, Oniseigi, are based around decay, meaning the spores will never be able to grow within that environment.

trivia

✿ The faceclaim for Sankeihana's spirit is Naraku from Inuyasha.

✿ The inspiration for Sankeihana is the Cordyceps fungi family, or the "zombie fungus." Aesthetic changes were made to match the deceptive nature of Hideyori's own beautiful, perfect exterior.

✿ The Zanpakuto name "Sankeihana" is meant to be a misnomer and double entendre, a purposeful deception to its true nature. "Sankei" is most commonly translated to 山系 ("Mountain Range") rather than the "Sankei" 散形 that forms part of Sankeikajo 散形花序 ("Umbel/Umbellate Inflorescence"). This means that when spoken, the common understanding of "Sankeihana" is misconstrued to mean 山系花 "Mountain Range Flower." Only when Hideyori finally says his Bankai's name, "Sankeikajoki" 散形花序気 ("Umbel Mind"), are people aware of the true characters used in the name,  deriving from "Sankeikajo" 散形花序 ("Umbel/Umbellate Inflorescence").

✿ The umbel flower resembles a network all connected at the center, and Hideyori's Bankai ability essentially places him in control of all of his extended "flowers" (read: infected people). The metaphor of how an umbel flower looks similar to a bundle of nerves, and the way Hideyori's power manifests, all lead up to the chosen name of "Umbel Mind" for his Bankai.

✿ The budding spores growing out of infected flesh most closely resembles those found in Advance Wars: Day of Ruin. The sole difference is that the flowers budding from Sankeihana's spores would remain pink and blue (as seen growing on the shikai form's parasol).