Bio and personality
Yumichika is the 5th seat in the 11th division squad. Though he could be higher, he chose the number 5 deliberately, as it most resembles the number 3, which he considers the most graceful of numbers. Unfortunately his best friend has the 3rd seat, so Yumichika settled into the number 5, though he could easily be 4th in strength, but considers the number 4 ugly.
This all due to the fact that Yumichika is a narcissist. In fact he takes it to a much deeper level. Yumichika bases his entire life around the love of beauty and grace. He considers himself the most beautiful member of the Shinigami, including women. The feathers he wears on his eyebrow are an adornment meant to give him a more distinctive look and to promote his relation to his totem animal: the peacock. This symbolism is also evidenced by his Zanpaktou's Shikai release, which has a tri-blade pattern that fans like the tail of a peacock, and in fact its release power turns it into a graceful fan of peacock feathers, though this is a closely guarded secret of Yumichika's.
Despite being a lover of beauty, Yumichika has a dislike of pretty women as he feels they intrude upon his own turf and move attention away from his own looks, in fact it is also possible that Yumichika might be homosexual, though this has not been elaborated on.
Yumichika, despite his pretty-boy demeanour is a member of the 11th squad at heart, and is a lover of battle, like all the 11th squad. He also possesses a very strong sense of honour and would never intrude on the battle of a fellow 11th squad member, as when they battle singly outside of a war, the 11th squad prefer to test their strength against an opponent one-on-one if given the chance.
Yumichika has been shown to have a great desire to get stronger and learn Bankai, like his best friend Ikkaku. He has been shown training and meditating with his Zanpaktou to try and learn its Bankai, and also shouting at it when his patience ran low, but his Zanpaktou is said to be 'every bit as narcissist and stubborn as he is'
The 11th Squad
The 11th division are the warrior division: they pride themselves as being the greatest fighters amongst soul reapers, and disdain the use of Kidou (demon magic) as they consider it a tool used by those too weak to fight themselves.
Yumichika's Zanpaktou is known as Fujikuzyaku.
In its base form it appears as a normal, though graceful Katana. It possesses no special abilities in this form.
In its second released Shikai state, it is shapes like a scythe or Kama, with triple blades jutting from the cross-guard in a fan-shape. This state gives it superior attacking and defensive abilities. It also allows him access to a hugely powerful Shikai ability. This ability is a very closely guarded secret of Yumichika's: in fact he has not even told Ikkaku, whom he trusts his life to. This is because his sword is a Kidou-type (Demon magic). As has been stated, Kidou is looked down upon in his squad, and he would lose honour and possibly even his place in the 11th squad if it were found out that his Shikai was not suited to his squad. Despite this, Yumichika's Shikai has shown quite possibly the most powerful Shikai ability in the entire Manga: when it is invoked his blade turns to a fan of peacock feathers and it instantly drains all of his opponents reiatsu, leaving just enough for them to stay alive (though this might be a deliberate choice of Yumichika's). The process involves their spiritual energy being drained out in the form of flowers which blossom, the petals of these flowers can also be eaten, the process of which heals Yumichika and gives him an excess of energy (and also leaves him feeling elated). The extent of the draining ability is unknown, but it was enough to instantly take down both a vice captain and an arrancer with no effort or accuracy involved other than line of sight.
Though Yumichika is a member of the 11th squad, who disdain magic, he has been shown to be a Kidou type by his Zanpaktou (which mirrors the spirit of the wielder). As a shinigami, it is highly likely that he has access to Kidou that he does not use, as all shinigami are required to know Kidou to graduate into one of the 13 protection squads except in a few extreme circumstances or strength. It is almost certain that Yumichika would be even stronger as a Kidou type warrior, as the shinigami's swords mirror their spirit.