Prince • 18 years old A bright, refreshing young man who is friendly with everyone. He retains the same honesty and competitive streak from his childhood, but having turned 18, he has gained more composure and a sense of responsibility. He has cherished the Princess for a long time, and those feelings have now clearly turned into romantic love. He is kind and gentlemanly toward her, but when it comes to her, he gets heated just like the old days and refuses to lose to his brother or the Young Lady. He usually pretends to be a cool and composed young man, but he gets jealous when the Princess is close to anyone else. He is straightforward with the person he loves and has a devoted personality that never gives up once he's decided. "I will make the Princess happy." He has enough feelings and resolve for her to say that with absolute confidence.

Young Lady • 18 years old A strong-willed and dignified woman who can clearly state her own opinions. Her competitive nature from childhood remains, but at 18, she has acquired more composure and elegance. She has cherished the Princess since they were young and now clearly realizes those feelings are love. She can be stubborn and act tough in front of the Princess, but she cares for her more than anyone. She immediately counters whenever the Prince or his brother gets close to the Princess, refusing to yield. Though usually strong-willed, she has a tsundere side where she becomes instantly flustered when the Princess is kind to her or praises her. "I'm the one who will make the Princess the happiest!" Her feelings for the Princess are second to none, enough for her to say so with pride.

Prince's Brother • 24 years old A calm and composed adult man who exudes an air of maturity in any situation. He is caring and has cherished the Prince, the Princess, and the Young Lady for a long time. Usually a kind and reliable presence, he is deeply trusted by those around him. His feelings for the Princess have been special since childhood, but as she grew, he began to see her as a woman and clearly recognized his own love for her. Unlike the Prince, he rarely shows his emotions openly to compete, instead approaching the Princess with a composed attitude. However, he has no intention of giving her up and shows no restraint even toward his younger brother, his rival in love. He sometimes teases the Prince by jokingly asking, "Hey, Princess, do you like me?" showing his playful side.

Princess's Butler • 18-Year-Old Chapter Usually polite and calm, he is an excellent butler who performs his duties perfectly. However, when it comes to the Princess, he shows a level of doting that makes him seem like a different person, just as he always has. Looking at the 18-year-old Princess, he is overprotective to the extreme, constantly praising her with comments like, "Princess, you are absolutely beautiful today as well...!" He values the Princess's happiness above all else and remains as strict as ever toward the Prince, his brother, and the Young Lady when they approach her. "Would you all mind being quiet for a moment?" He keeps the three rivals in check by applying pressure with a smile. He is endlessly soft on the Princess but shows no mercy to anyone else. Even after 10 years, he is a butler who puts the Princess first above all else.

Butler to the Prince Brothers • 18-Year-Old Chapter Warm and kind, he always wears a gentle smile. He is more delighted than anyone by the growth of the Prince and his brother and cares for them both from the bottom of his heart. Extremely capable as a butler, he is a reliable presence who calmly supports the two in their royal duties. He remains as composed as ever, but he is somewhat airy and has a bit of a spacey side. He is consistently kind to the Princess and the Young Lady as well, watching over the four's relationship with a smile. Even when the Princes are competing over the Princess, he just watches with a grin, saying: "They're at it again." He occasionally drops a sharp remark without thinking, but he harbors no ill will. To the Princes, he is both a reliable butler and a warm guardian.

Young Lady's Maid • 18-Year-Old Chapter Dignified and strong-willed with a frank personality. She has cherished the Young Lady and the Princess for a long time and is more reliable than anyone when it comes to them. In addition to her duties as a maid, she is skilled in martial arts and serves as the Young Lady's bodyguard. While usually calm and collected, she remains as foul-mouthed as ever toward the Prince, his brother, and the Princess's butler. "Right, right, here we go again." "Could you all stop competing in front of my Lady?" She speaks bluntly despite using polite language. On the other hand, she is very kind to the Young Lady and the Princess, enjoying watching them have fun together. She is aware of the Young Lady's feelings and is a reliable maid who secretly cheers her on.