Finn is the prince of a small foreign country whose true gender has been concealed from the public. She initially appears as a reluctant participant in a series of arranged marriage meetings Kei's grandfather sets up for Hikari.
Finn "falls" for Hikari on the spot, since she fits the exact description of Finn's ideal person: a woman with long dark hair possessing a sweet yet tough personality who looks good in a red dress. After helping Hikari escape, Finn follows her to Japan with the intention of proposing to her. The SA later discover that Finn's mother fits the description of the ideal person Finn wants; Hikari tells Finn that it's a wonderful thing to look up to her mother so much before adding that she and Finn can still be friends. Afterwards, Finn enrolls in Hakusenkan and tries using Ryuu to get closer to Hikari, but ends up becoming very good friends with him. Finn's exact ranking in Hakusenkan has not been revealed, but it is known that she is in C class. She first appears in chapter 47.
Ryuu discovers not long after meeting Finn that the prince is actually a girl; in Finn's country, the law states that the country must be ruled by a male and if the heir is a female, she will be raised as a male. Upon explaining this to Ryuu, she asks that he keeps her secret as they will be severely punished if it is revealed. Shortly after Hikari discovers Finn's secret, Finn and Hikari attempt to convince Finn's father to allow Hikari to return to Japan rather than face life imprisonment in Finn's country. The issue is resolved when it is revealed that Finn's mother is pregnant and the baby will be a boy; Finn is revealed to be a girl to everyone else and her unborn brother will become the heir to the throne.
Finn is usually cheerful and smiling, but can get on her tough side when someone will almost figure out she's a girl. She is revealed to be light when Ryuu accidentally carries her. Also Sakura's dog, who only likes girls, hates Ryuu and really loves Finn, which makes the S.A. gang very curious about Finn's gender. She is very protective of her secret. She likes to think of herself "different" from other girls and considers herself a boy, but not until Ryuu tells her that he will always see her as a girl in his heart.
Ryuu is Finn's boyfriend in the manga. They make a cute couple and are both always watching out for each other. The two of them are like 'birds of a feather'. When Finn is hanging out with Ryuu in front of the twins, the twins become very protective over Ryuu, for they're usually fighting over him.