|Affiliation||Gotei 13, Soul Society, Kuchiki Family|
|Position||Captain of the 6th Division
28th Head of the Kuchiki Family
|Previous Partner||Ginjiro Shirogane|
|Base of Operations||6th Division HQ, Kuchiki Manor, Soul Society|
|Relatives||Ginrei Kuchiki (grandfather, deceased)|
Sojun Kuchiki (father, deceased)
Hisana Kuchiki (wife, deceased)
Rukia Kuchiki (sister-in-law/adoptive sister)
Byakuya has slate gray eyes and long black hair, which he keeps up in intricate white headpieces called kenseikan, which symbolize his nobility as the head of the Kuchiki Clan, wearing one on top of his head and another on the right side. In addition to the standard captain uniform, he wears a white scarf, which is made from silver-white, windflower light silk and is a family heirloom, having been handed down from generation to generation and given to each head of the Kuchiki Clan. The scarf alone is worth ten mansions in the Seireitei. He wears fingerless white tekkou which only cover the back of his hands.
Byakuya is calm and aristocratic, as expected of his class. He rarely, if ever, raises his voice, even when he is angry, and his demeanor is always calm, to the point of almost never smiling. He is also a staunch believer in law and order, and will destroy anything he sees as a threat to it, though despite this, he is an honorable man. He deeply cared for his deceased wife, and clearly married for love since she was a commoner, even risking facing disgrace at doing so, suggesting that his titles and prestige haven't made him completely departed from the realm of reality.
In his youth, Byakuya was a short-tempered brat who was obsessed with training and never devoted time to having fun, to the point of which even his stern grandfather, whom he respected greatly, would occasionally urge him to lighten up; he would always refuse and insist that he was carrying on his family's legacy.
Byakuya was born into the Noble House of Kuchiki, and was trained from birth to become the family's head and captain of the 6th Division. During his youth, Byakuya was a competetive, excitable, short-tempered boy who was so obsessed with proving himself through training that his grandfather, Ginrei Kuchiki, would often try to convince him to lighten up every now and then. Yoruichi Shihōin, then captain of the 2nd Division, would often interrupt his training sessions and provoke him into chasing her; it was through this impromptu training that Byakuya became extremely proficient at Shunpo. He would hold a grudge against Yoruichi for the rest of his life.
Some time later, Byakuya's father and grandfather both died, and he became the head of the Kuchiki Clan. He fell in love with a commoner named Hisana and married her, despite his clan's objections. Hisana passed away not long afterwards from an unknown illness. On her deathbed, she made Byakuya promise to find her younger sister, Rukia, and take care of her. Byakuya eventually found Rukia and made her his adoptive sister, again in defiance of his clan's wishes.
- Despite being Rukia's adoptive brother instead of sharing any blood relation to her, he shares her drawing skills, or lack thereof.