Byakuya Kuchiki (朽木 白哉 Kuchiki Byakuya ) is the captain of the 6th Division in the Gotei 13. His lieutenant is Renji Abarai. He's also the most important person in the Kuchiki Clan. Byakuya first appears on a mission with his lieutenant, Renji Abarai, to capture Rukia Kuchiki and kill Ichigo Kurosaki. They succeed in retrieving Rukia, and would have easily killed Ichigo, if not for Rukia's intervention, pleading for Byakuya not to give the finishing blow. Byakuya later interrupts Ganju Shiba and Hanatarō Yamada's attempt to rescue Rukia and, later on, Renji's attempt. When Ichigo succeeded in rescuing Rukia, he and Byakuya have an extended battle, where both use their bankai. However, Ichigo's inexperience with his new release and Byakuya switching to a more powerful form leaves Ichigo at a disadvantage. It was through the temporary emergence of Ichigo's inner hollow that evened the odds out once more.
Byakuya, as the 6th Division Soul Reaper captain, is skilled in all forms of Soul Reaper combat. In keeping with his rank, Byakuya's abilities allow him to defeat opponents of lieutenant level Soul Reaper without much effort.
Of particular note is Byakuya's speed: he is skilled in the use of flash steps, having trained with (but never surpassed) Flash Master Yoruichi Shihōin. Yoruichi also taught Byakuya some techniques of her own creation involving flash steps, including one called utsusemi (空蝉, lit. empty cicada, in reference to their molting), which allows Byakuya to move out of harm's way while leaving an afterimage behind. One of Byakuya's favorite techniques, as described by Renji, is senka (闪花, lit. Flash Blossom), a flash step combined with a spin to quickly move behind the enemy, followed by a combination of two quick thrusts. In his battle with Zommari Leroux, he is able to maintain his composure and fight at full speed, despite being forced to cut the tendons in one of his legs and arms to prevent Zommari from gaining control of them.
Byakuya has also displayed knowledge of high level kidō spells, able to cast spells up to number 81 without the incantation. He is adept at using them strategically, such as disrupting the movement of Renji's bankai with a well-timed fire spell and damaging Ichigo's right arm by using a low-level lightning spell at point-blank range to burn a hole through his shoulder.