A high-ranking spirit of wind contracted to the Barrier Mage. Her nickname is Lin. She usually takes the form of a maid but can transform into other shapes, most often a bird. She supports Monica's top-secret mission by acting as a messenger between Monica and Louis. She is apparently still studying how to behave like a human.

One of the Seven Sages, known as the Barrier Mage. Since he was chosen as a Sage at the same time as Monica, he calls her "Colleague." Although he belongs to the First Prince's faction, the King ordered him to guard the Second Prince; he ended up pushing that duty onto Monica. He seems unable to stand up to his beloved wife, Rosalie.

The Second Prince of the Kingdom of Ridill. He is a third-year student in the high school division of Serendia Academy, the kingdom's most prestigious school, where he serves as the Student Council President. His maternal grandfather is the Duke of Crockford, one of the most powerful men in the country. He is embroiled in the succession struggle for the throne and is frequently targeted by assassins.

The Vice President of the Serendia Academy Student Council. A third-year student. Born to a father of marquessal blood and a mother of commoner origin. After his father's death, he was adopted into the distant Highorn Marquess family and lives away from his mother. He deeply admires Felix and is a serious, diligent worker who supports the president. He has a talent for magic and uses ice spells.

The Secretary of the Serendia Academy Student Council. A third-year student. The eldest son of the Earl of Darzvey. He has a strong belief in social hierarchy, acting on the conviction that "nobles should act like nobles and commoners like commoners." He is strict with both himself and others. He has known Felix since childhood. He takes chess as an elective and is one of the top players in the school.

A Secretary of the Serendia Academy Student Council. The daughter of the Marquess of Shellbury. She is academically excellent and fluent in multiple languages. Her behavior and conduct are said to be perfect, and she is considered one of the three great beauties of the academy. She is a childhood friend of Felix, and rumors suggest she is the most suitable candidate to be his fiancée.

General Affairs for the Serendia Academy Student Council. The son of Baron Maywood, a family known as the "House of Mediators" for their role in arbitrating and negotiating. A second-year student like Monica. He is gentle, approachable, and serious. While he can be easily swayed by others, he proves his worth as a reliable supporter behind the scenes.

A second-year student. She has a strong personality and doesn't pay any mind to petty gossip. Coming from a family of merchants, she is well-versed in the latest trends. She was the one who reached out to the transfer student Monica, becoming her first friend.

Monica's familiar. He usually takes the form of a black cat but can speak human language and transform into a human form.