The 6th division handles relations between the Gotei 13 and other branches of Soul Society, particularly the noble families. In that respect, it's no surprise that it consists mostly of the sons and daughters of noble families. Vice-captain Abarai Renji is something of an aberration, which seems to please him.
Captain: Kuchiki Byakuya
Captain Kuchiki is the 28th head of the noble Kuchiki clan, one of the four great noble families in Soul Society. As such, Byakuya acts in an aristocratic manner – he seems always serene and apathetic towards other people, even those close to him. He is also extremely calm, even in battle, and is very seldom surprised by even the most drastic of actions.
Byakuya strongly believes in law and order; as the head of one of the great noble families and as a captain in the Gotei 13, he has always worked hard for a peaceful society. He feels that if someone in his position doesn't follow the rules as a good example, then no one will follow them; accordingly, in order to maintain the order, all law-breakers must be punished, even if that goes against his own wishes. Despite his powerful adherence to the law, however, it is know that he went against his family's wishes when he took a wife from the Rukongai some fifty years ago. The woman since passed away, however – thought by many to be part reason for his cold demeanour.
Byakuya wears the standard captain uniform along with a white headpiece called a kenseikan (symbolizing his noble rank as the head of the Kuchiki family) and a white scarf made by the master weaver, Tsujishirou Kuroemon III, which is an heirloom of his family.
Zanpakutou: Senbonzakura (lit. "Thousand Cherry Blossoms")
Its shikai command is "scatter". When released, Senbonzakura's blade separates into thousands of slender tiny blades, which then fly away from the hilt. While the blades are too small to see normally, they reflect light in such a way as to appear as cherry blossom petals. Byakuya can control the blades at will, allowing him to shred opponents at a distance and break through almost any defence. While Byakuya can control the blades with his mind alone, using his hands allows him to do so more effectively, making the blades move almost twice as fast.
Byakuya's bankai, named Senbonzakura Kageyoshi (lit. "Thousand Cherry Blossoms' Grim Scenery"), is essentially a much larger version of Senbonzakura's shikai. To activate it, Byakuya drops his sword. The sword passes through the ground and two rows of giant blades rise up from the ground behind Byakuya or surrounding the enemy. These then scatter into millions of tiny blades. The number of blades is great enough that Byakuya can use them for defence and offence at the same time. He commonly forms them into large masses of blades to crush opponents. Like with his shikai, its attack is triggered with the phrase "scatter".
Byakuya's bankai also has several forms, achieved by arranging the blades in different patterns, though the exact nature of these is unknown to most shinigami.
Vice-captain: Abarai Renji
Formerly of the Rukongai, Vice-Captain Abarai came to the Gotei 13 via the Shinigami Academy. Abarai's swordsmanship skills meant he was admitted into the top class of the shinigami academy when he entered, despite his inability with kidou. During his time at the academy, he developed lasting bonds several other students who would also go on to become vice-captains – Hisagi Shuuhei, Kira Izuru, and Hinamori Momo.
Renji, Kira and Hinamori served under Sousuke Aizen and Gin Ichimaru in the 5th division, after which Kira and Hinamori were put under Ichimaru and Aizen in the 3rd and 5th divisions respectively. The rebellious Renji was moved to the 11th Division and eventually rose to the 6th seat. Renji's transfer to division 6, and subsequent promotion only happened very recently, within the past year.
Renji is one of the few vice-captains in Soul Society to have unlocked his sword's bankai. Despite this, however, he has still not been promoted to the rank of captain, possibly because of his rebellious and irresponsible nature.
Zanpakutou: Zabimaru (lit. "Snake Tail")
Zabimaru's shikai command is "howl"; when released, it transforms into a broad, segmented blade with a pick-like protrusion on each segment. The segments are connected by a stretchable thread, making Zabimaru more useful as a whip than an actual sword, though it can serve as a regular sword just as easily.
Zabimaru's bankai, Hihiou Zabimaru (lit. "Baboon King Snake Tail"), transforms Zabimaru into a massive version of its shikai form resembling a skeletal snake. Zabimaru gains many more segments, which are much larger than in its shikai form, and also gains a snake-like head about the size of a small car. Renji is also slightly transformed, gaining a fur cowl around his neck. Unlike its shikai, Zabimaru's segments are held together by Renji's spiritual power, allowing him to separate and reattach them at will. The segments themselves are extremely tough, making it extremely difficult to destroy Zabimaru. Even if a segment is damaged, Renji can simply detach it and reform Zabimaru.
Zabimaru itself, in bankai form, does not literally "cut"; Renji usually catches his opponent with the snake-head of his weapon and smashes his opponent into the ground with it. The head has also proven capable of inflicting heavy damage through biting.