Byakuya is an arrogant and serious young adult who originally saw himself to be more superior than the others due to being the heir to an extremely successful family business. He is extremely reluctant to admit to any mistakes he might have committed, and constantly refers to the other students as "amoebas" and "plebeians". He has a deviously manipulative tendency, as he often expressed irritation from Toko Fukawa and Genocide Jack's obsessive behavior towards him, but often used it to his benefit by ordering them around. He has also betrayed their trust more than once for his own personal gain.

He is often cold, blunt, and reserved, preferring to work alone and mocking the others' attempts to be cooperative, even bluntly stating that they are not friends. However, he does not appear to be as actively mean as he seems.