Mikoko is a woman of average height and figure, having shoulder-length brown hair with bangs parted in the middle. She has a large nose (as most Kaiji characters have) and a large mouth with light pink, somewhat thick lips.
She's shown to be a somewhat rebellious girl, telling her father off when she comes home later than she should've. Towards Kaiji she's very sweet and loving, making him sandwiches and wanting to be near him at all times. However, it's shown that she can get annoying (to Kaiji, at least).
Tobaku Hakairoku Kaiji
She is not personally seen in this arc as she and her mother left her father due to his financial issues. She is only seen through flashbacks as her father thinks of her and his motivation to win at the Bog.
In the anime series she is shown prominently in the ED, interacting with Kaiji.
Tobaku Datenroku Kaiji
After her father wins from the Bog, he spends the money to buy his dream house which managed to sway his wife and daughter to live back with him. However due to Kaiji lacking any money after the gamble, Sakazaki offers him to stay with them.
As time passed, Kaiji becomes lazy and unmotivated to work. Sakazaki becomes irritated by his behavior and eventually kicks him out by giving him ¥3 million. She is seen from the window of their house, saddened, as Kaiji leaves to gamble once more.
Tobaku Datenroku Kaiji: One Poker-hen
She is shown drawing a manga about Kaiji returning to her promising to abandon gambling only to be drawn in the next panel returning to gambling on a pachinko machine. She rips the manga apart realizing the conclusion she drew.