Sonju is an outcast along with Mujika.
Sonju was once a Demon Prince.
He is incredibly strong, fast and intelligent compared to most Demons and far more intelligent than humans.

Demon, was a Demon Prince.  Calm and composed.

Kokushibo for the most part, is rather cold and distant.  He shows a great amount of respect and loyalty for Muzan Kibutsuji (Demon King)
Kokushibo has seen and experienced many traumatic situations throughout his life, including from when he once was human.  Kokushibo secretly has a soft, kind and understanding side.  Although; not commonly exposed.

Upper moon one, demon, cold and distant.

Nakago is the general of the Kutou Army as well as being a 'Celestial Warrior of Seiryuu.''
He his extremely powerful both spiritually and physically, showing little to no remorse or mercy.
His goal is to take revenge on those who have caused him great suffering, by any means necessary.