Prince Yuuto of Fall has a lot on his mind due to the upcoming marriage of his sister, Princess Fana, to Prince Seiwelt of the neighboring kingdom of Rhode. He must pay for their travel expenses and his sister's dowry, among other things. However, Yuuto—and by extension, the kingdom of Fall—carries a debt exceeding two billion gran. He cannot bear to bring shame to his sister's reputation and therefore continues to spend money on the wedding, all the while at a loss as to how to repay his accumulated debt.

Although Yuuto is friends with the very wealthy Prince Tajesu of Nisabem, he is determined not to accept any charity. Despite Yuuto's feminine appearance, which makes him the subject of much teasing, he performs work as a mercenary when and where he can. Yet somehow, he continues to incur new debt that outweighs what little he earns from completing jobs. At his wit's end, Yuuto hears about a bounty of fifty million gran for the successful capture of the boss of a notorious thief gang. He seizes this opportunity and brings his assistant, Iru Grasse, as well as Prince Tajesu along on his quest.