A detective at the Shirakaba Detective Agency. His assistant, Sakura, is his half-sister. He is characterized by an exaggerated way of speaking—using phrases like "Well, well!" or "Good grief!"—and grand gestures. He is half-Russian and half-Japanese, though he keeps this a secret. His skills as a detective are top-tier, primarily taking requests from the wealthy. He has a sturdy build and is skilled in martial arts, often striking others with his walking stick. Sakura thinks he looks like he's having fun when he corners people.

The office manager and assistant at the Shirakaba Detective Agency. Banri's half-sister. She is not of mixed race. She possesses excellent insight and conducts steady, thorough investigations in contrast to the theatrical and flamboyant Banri. She is quite sharp-tongued toward her older half-brother.

The master of the Tachibana house and a Count. A man approaching old age with a solemn atmosphere. He is obsessed with his daughter, who was born late in his life. His excessive doting is a common topic of gossip. He has no interest in his eldest son, Yukiya, who wishes to pursue art. He is willing to do anything for his only daughter. Furthermore, there are hints that he suspects she may not be his biological child.

The eldest son of the Tachibana family and a painter. He was originally supposed to inherit the title but withdrew from the succession race. He lives in a detached wing and seems to care for his sister, who is doted on by their father. He keeps Tatsuhiko close by in case anything happens to his sister.

The third son of the Marquis Tsubaki family. A military man with distinctive almond-shaped eyes and a friend of Yukiya. He has been fond of Yukiya's sister since they were children and acts as a sort of guardian for her.

A butler serving the young lady, with round, bright eyes. Though he still retains a boyish appearance, the young lady likes him and keeps him close. He has a gentle personality and is very attentive to detail.

A candidate for the young lady's fiancé. A man who built a fortune in the mining industry in a single generation. Since he has money, he seeks the social standing of a noble bloodline and has proposed marriage.

The head butler of the Tachibana household. A distant relative of the late mistress. Surprisingly, he is a man of action and can be quite aggressive. He has a bit of a muscle-brained streak.

The estate's gardener. A young man who cares about the young lady. He stays with the Tachibana family out of gratitude for being taken in by the late mistress.