Ai Hayasaka

A female student from Class 2-A, later Class 3-A. She is the daughter of a senior member of the Shinomiya Group and is a quarter Irish. Her official birthday is April 2nd, and she has blood type AB.

She serves the Shinomiya family as a maid and is Kaguya's personal attendant. Her family has pledged loyalty to the Shinomiya family for generations, and she has been attending Shuchiin Academy since elementary school to support Kaguya during her studies. She grew up with Kaguya almost like sisters, and she considers Kaguya more of a little sister than a master. Kaguya relies on her and often presents her with difficult tasks, but Kaguya also thinks she has a similarly bad personality. She does not think well of Kaguya's father, Gan'an, who treats Kaguya coldly.

Usually calm and composed, she switches her personality depending on the situation. At school, she changes her attire and speech to act like a typical "gyaru." She often gets involved in Kaguya's schemes against Shirogane, keeping their relationship a secret from him. She is loyal to her duties and highly capable, but she struggles with the unpredictable Chika. She has a tendency to be a "mama's girl," as seen when she cried and sulked upon hearing her mother couldn't attend the sports festival.

She finds the slow progress in Kaguya and Shirogane's relationship frustrating and sometimes tries to push it forward. She is well-paid for her job as Kaguya's attendant, earning a monthly salary of 500,000 yen and an annual bonus of 4 million yen, with over 40 million yen saved after ten years of service. However, due to the demanding nature of her job, she expressed a desire to change careers in a career survey. She enjoys building custom PCs and is knowledgeable about IT. When Kaguya's flip phone broke, she accompanied her to buy a smartphone and got excited looking at the latest models, despite noting that high school girls usually prefer iPhones.

Originally sent by the Shinomiya family's eldest son, Kōkō, to be Kaguya's attendant and spy on her, she decided to quit her job during a school trip due to guilt. She got involved in an incident caused by the third son, Un'ō, which revealed her spying to Kaguya, but she was forgiven and became friends without a master-servant relationship.

She has told Kaguya that "men are ultimately driven by sexual desire," but she has no dating experience herself. However, she has a romantic side typical of a teenage girl and once suggested a Yokohama date plan to Ishigami through Kaguya, only for Ishigami to point out its flaws and realize she had no dating experience.

School Persona: Ai Hayasaka

Her appearance at school. She is a lively "gyaru" who enjoys fashion and skirts the edge of school dress codes.

Smithy A. Harsaka

A fake name used when Shirogane visited the Shinomiya household. She changed her hairstyle and wore colored contacts to alter her eye color, and even padded her chest. She claimed to be a student at Phyllis Girls' Academy and occasionally worked part-time at the Shinomiya household. Later, she revealed to Shirogane that she was investigating Kaguya on orders from the Shinomiya main family, showing a genuine expression. She then exchanged contact information with Shirogane, expressing a desire to be friends.

Harsaka-kun

Her appearance when meeting Chika while serving the Shinomiya family. To avoid being recognized as the same person at school, where she is close to Chika, she dresses meticulously as a boy. She has a backstory of being a war orphan who graduated from Harvard University at an accelerated pace and works as a butler. Chika suspects her of having a homosexual relationship with Shirogane.