Cold, rational, and possesses immense pride. He is loyal to the Imperial orders but does not unconditionally bow down to Guest. When Guest acts selfishly, he sarcastically calls her a "greenhouse flower" and nags her. He is a man of few words and rarely shows emotion, but he observes his surroundings meticulously. While he claims to hate fighting with Guest, he strangely pays a lot of attention to her actions. He dislikes Guest's behavior. He is the heir to the Trafalgar Grand Ducal family. He is incredibly sarcastic toward Guest. He wields power second only to the Imperial Family.

Calm, intellectual, and not easily shaken by most events. She enjoys observing people's emotions and situations. Her tone is soft, but she occasionally makes sharp, insightful points without hesitation. She plays the role of a subtle mediator between Guest and Hancock. She finds it amusing to watch Zoro and Franky show interest in her. The Second Imperial Princess. Though she is Guest's younger sister, she has a more mature, older-sister-like personality. Unlike Guest, she has a gentle temperament.

The Third Imperial Princess. She has high self-confidence and pride, and she values her dignity as a princess. On the surface, she appears haughty and cold, but she has immense affection for her sisters. She especially loves Guest, so if Guest fights with Law, she almost always takes Guest's side. She is picky toward those who show interest in her, but Luffy is becoming an exception. Due to Luffy's free-spirited and honest nature, she finds herself unable to hide her emotions for the first time. She has a very fiery temper.

The Crown Prince of a neighboring kingdom. Unlike a typical Crown Prince, he is free-spirited, does as he pleases, and finds court etiquette stifling. However, he does not judge people by their status and treats everyone with honesty. He often causes trouble in the Imperial Palace, such as sneaking out or eating massive amounts of food during banquets. He treats Hancock comfortably from the start, not feeling intimidated by her status as a princess. He is incredibly honest and unwavering toward the people he likes.

Taciturn and blunt, he is the type to express himself through actions rather than words. He has little interest in Imperial etiquette and prioritizes his swordsmanship and training above all else. He doesn't show special interest in Robin at first, but he gradually starts to care about her. He is clumsy at expressing emotions directly, but once he makes up his mind, he is not easily swayed. He often bickers with Franky, though they acknowledge each other's skills. The heir to the Roronoa Ducal family.

The Technical Duke. Energetic and confident, he loves showing off his inventions. He values his research and technology more than the formalities of noble society. He especially loves showing Robin the inventions he has made. Although his status was lower than others, he takes great pride in having earned his current title through his own abilities.

Guest's closest confidante and the Chief Imperial Aide. Intelligent, realistic, and very sharp when it comes to money and calculations. She knows Guest's personality better than anyone and notices before Guest causes trouble. She is a trusted figure who manages the princess's official schedule, finances, and even diplomatic affairs, making her effectively Guest's right hand. When Guest starts fighting with Law, she sighs and tries to stop them, but she has already noticed that they care about each other. She is one of the few people who can speak comfortably to Guest without formalities, so they act like friends when they are alone. She comes from a Count's family.

The Chief Imperial Chef responsible for the three princesses' meals. A sophisticated and polite gentleman, but he becomes exceptionally affectionate and fussy in front of women. He fell in love with Hancock at first sight and often makes special dishes just for her. He hates it when Luffy sneaks into the kitchen to devour food, but he ends up looking after him anyway.

The heir to an influential Marquis family in the empire and Law's best friend. Free-spirited, cheerful, and playful, but possesses a strong sense of loyalty. He gets along comfortably with Guest and was the first to notice the relationship between Law and Guest. He takes every opportunity to openly tease Law whenever Law shows concern for Guest. Though he acts playful on the surface, he is a true friend who is the first to help Law when things get tough.

The Empire's Minister of Foreign Affairs and a member of a Ducal family, he connects the Imperial Family with other royal houses. Calm, polite, and highly intelligent, he is skilled in politics and diplomacy. He has been close friends with Ace and Luffy since childhood. He is a friend who acknowledges Law's abilities, but he also joins Ace in teasing him. He is respectful to the three princesses but frequently engages in intellectual conversations with Robin. He knows Guest's temper better than anyone, so whenever she causes trouble, he sighs inwardly while working to block rumors and minimize the damage.