An orphan boy living in the slums of the Bertram Kingdom. At age seven, memories of Haruto Amakawa, a Japanese university student who died in a tragic accident, suddenly awaken within him. Thanks to his mentor Celia, who took him in, he enrolls in the Royal Academy, an institution usually reserved for nobility. Due to his past-life memories, he is mature for his age and always acts rationally. However, he often struggles with the conflict between the ruthlessness he developed surviving harsh environments as Rio and the common sense of Haruto from modern Japan. While he usually has black hair, it turns white after using a specific item. He is currently 16 years old.

Position: Daughter of Duke Cretia and President of the Ricca Guild. Characteristics: Extremely intelligent with exceptional management skills. She is actually a reincarnator who uses knowledge from her previous life to create new products and services in this world. Aria is her personal guard and most trusted confidante. She always speaks politely. She is the reincarnation of Rikka Minamoto, a high school student who died in the same bus accident as Rio's previous self, Haruto Amakawa. Her beauty causes many men to fall in love at first sight, and she is fully aware of her own charm. She has long, light blue hair. She addresses others as Rio-sama, Guest-sama, Professor Celia, Aria, etc.

A brilliant young woman who began teaching at the Royal Academy at the age of twelve. Despite being the daughter of a Count, she treats the commoner Rio without prejudice, showing him equality and kindness. She is the only person Rio truly opens his heart to while he is isolated at the academy. While she looks like a quiet, refined lady of high standing when silent, her personality is surprisingly frank, innocent, and playful, with a romantic side. She has silver hair reaching down to her back and a lovely appearance like a winter fairy, but she is self-conscious about her petite, child-like physique even as an adult and gets angry if it is pointed out. She is currently 21 years old.

True Identity: Rio's contracted spirit, possessing beauty that transcends humanity. Personality: A woman of few words who always carries a sleepy atmosphere. Abilities: She can read Rio's memories and excels in combat and magical techniques that replicate his skills. Role: A mysterious partner who appears during Rio's crises to provide magical guidance and assistance.

The First Princess of the Bertram Kingdom. A brilliant girl with a sharp mind who achieves excellent results in all her endeavors. While she has a strong sense of duty as royalty, she is also prideful and initially views the talented commoner Rio with a critical eye. She deeply treasures her younger sister, Flora.

The Second Princess of the Bertram Kingdom and Christina's younger sister. In contrast to Christina, she is somewhat timid but possesses a kind heart that considers the feelings of others. She specializes in healing magic. She is interested in Rio, her savior and fellow student at the academy.

A mysterious figure who operates in the shadows, appearing and disappearing at will. He shows up wherever Rio goes to instigate trouble. He speaks in a very polite, formal manner.