Yumichika is the narcissist friend of Ikkaku Madarame. During their past the two went throughout the Rukongai together looking for fights, and one day Ikkaku lost to Kenpachi Zaraki. After a speech given to them by him about living to kill the one who failed to kill them, and later after hearing news of Kenpachi becoming a captain, the two joined the 11th Division to serve under him. Yumichika wanted to become the 3rd Seat, since he thought three was the most beautiful kanji, though Ikkaku took it, so Yumichika took 5th Seat, thinking that 5 looks almost like a 3. It is not entirely clear if Ikkaku maintains the seat due to if he is superior to Yumichika, or if Yumichika allows him to have because of their friendship. He has colorful feathers on his eyelashes and eyebrow, and shiny skin and hair, giving him a rather womanly appearance in the early manga. Yumichika judges everyone and everything by beauty, and is also incredibly vain. However, he is at times shown to be caring and helpful to others.
Yumichika's zanpakutō is Fuji Kujaku (藤孔雀, lit. Wisteria Peacock). The shikai command for Fuji Kujaku is "bloom" (咲け, sake?, "bloom for me" in the English adaptations). In its shikai, Fuji Kujaku takes the form of a sickle-shaped blade, or falx, distinguished from the khopesh by the cutting edge being located on the inside. A hinge at the hilt allows Fuji Kujaku to split into four identical blades. Although Yumichika doesn't admit it to his 11th Division comrades for fear of being hated, since 11th Division zanpakutō are generally used for direct attack, he has a kidō-type sword. By using the command sakikurue (裂き狂え, lit. tearing deviate), Fuji Kujaku flares up and takes the appearance of many peacock feathers, after which it drains the opponent's spiritual power, allowing him to beat even lieutenant-level fighters with apparent ease. It is also assumed he's trying to learn his bankai, though Fuji Kujaku is just as narcissistic as Yumichika himself, leading Yumichika to comically yell at his sword while trying to break it against a boulder.
(Source: Wikipedia, Bleach official character books I-III)
