Caesar is the black-haired prince of Belquat, and is married to Nakaba. The two really don't like each other at first, but their feelings for each other gradually increase.
Even though he's the second son, his elder brother Cain was stripped of his rights to the throne, due to his being born with blonde hair (his mother was blonde, and a mistress of his father the king). Caesar then obtained the rights to the throne. Due to this, the brothers have a certain amount of hostility towards each other.
Cain's fiancee, Louise, is in love with Caesar. This only adds to the animosity between them. Loki kills Cain during the attack on the Ajins to protect Nakaba, who had a vision of Lemilia being slain by Cain and jumped in front of his sword (at the time of the vision, Nakaba did not recognise the person in her vision). Now he is under suspicion of murder. He also dislikes Loki, who has not only tried to kill him several times, but is also affectionate towards Nakaba. He is quite jealous of sub-persons, who can be close to Nakaba without hurting her.
In the beginning of the story, Caesar has long black hair and what appears to be brown eyes. After Nakaba cuts her hair short, he does the same, since he couldn't protect her hair. He also has pierced ears.
Caesar is arrogant and domineering on the surface. He has a great dislike for subpersons, due to the fact that they are born with heightened skills and senses. He is also extremely insecure, though he does not show this. He says that akage (those with red hair) are worthless, though he is affectionate of Nakaba.