Mika Asagi

Mika Asagi is the series' main character. Because of Big Daddy's noble blood in her, she is the future boss of Millennion and thus, is respected by most people in Biscoe's Millennion, including Biscoe himself. Having lost her parents, Mika grows very attached to Brandon, her parental figure. She is upset at how Millennion treats Brandon after he is labeled as a traitor for protecting Harry, the man who murders her parents.

Personality
Being young, Mika is naive and often fails to see the reasoning behind something. This frequently causes her to complain about the way Millennion operates, such as Biscoe's and Norton's way of treating Brandon. Because what they do is harsh, Mika automatically sees them as monsters, although they actually are just trying to enforce the law within MIllennion. Thanks to Brandon, she gradually learns.

Like her mother, Maria, Mika is a kind-hearted girl, though her naivete plays a role in amplifying this. She still forgives Brandon and expresses how much she loves him despite knowing that Brandon was actually helping the murderer of her parents. She is also always concerned of Brandon's tendency to get involved in dangerous jobs. However, Mika is also short-tempered and brazen at times. This, though, only shows when Brandon is mistreated.

Being kind, Mika sometimes fails to bring herself to fight properly. In For the Sake of Survival, as Brandon cripples a few thugs (physically and mentally) to reduce the risk of them hurting Mika, she refuses to attack. She thinks that attacking injured and terrified men is unfair. However, she soon grows out of it when Brandon tells her that the city of Billion is just as harsh as the wilderness.

Mika is also a strong-willed girl, which is mainly driven by her desire to protect Brandon, her parental figure. In order to save Brandon in Decisions, Consequences, and a Second Chance, Mika bites a Millennion guard's hand just so that she can arrive at the scene to stop the assault.

Throughout the series, Mika is rather cowardly, but as noted by Brandon, her courage always shows when the situation calls for it. Usually when Brandon is in trouble, she will rarely give a second thought when rushing into the scene.

Brandon Heat
Mika no longer calls Brandon 'Grave' because she truly thinks him of her family. She always does her best to provide support and comfort for Brandon, although she may occasionally poke fun at him. She views Brandon as her 'daddy' and is also very protective of him. She has saved Brandon several times with her authority in Millennion.

Biscoe
Although Mika is initially hostile towards Biscoe due to the mob boss treating Brandon badly (which is actually just Biscoe's attempt to preserve his dignity as a mob boss), thanks to Brandon's guidance, she starts to behave better.

Norton
Mika is also initially hostile towards Norton, but she does respect him. However, Mika never respects Norton as much as she respects Biscoe, as Norton is never friendly towards Brandon.

Dr. William Rutherford
Mika often sees Dr. William as more of an older brother. However, whenever William accidentally hurts Brandon's feelings, Mika will not hesitate to scold him.