Question: are byakuya and rukia related?
Answer: Hisana asked Byakuya to find and adopt her biological sister, Rukia, whom she had abandoned as a baby, as her final wish. She made him promise he would not tell Rukia she is her sister. ... Less than 49 years ago, not long before Rukia joined the Gotei 13, Byakuya became the captain of the 6th Division.