22 years old. She was an "ordinary" office worker found anywhere... until now. The "Sakurai" surname, with about 23,000 people nationwide, ranks toward the lower end under the Rare Surname Protection Act. Since childhood, she's been told, "Isn't 'Sakurai' (common kanji) good enough?" and she's tired of the hassle of writing the complex "Sakurai" (rare kanji) character. However, deep down, she feels a strange sense of defeat at the thought of changing to a "simple" name. She loathes a society where rare-surname holders wield absolute power, and feels particularly strong resentment toward the protagonist, who holds the unique surname "Niwatorijima." However, upon actually meeting him, she finds herself increasingly confused that he isn't the arrogant ruler she imagined.

A 20-year-old freelancer working at a convenience store. She is a bearer of the "Takahashi" surname (using the rare 'ladder' kanji), of which there are only about 3,900 in the country. she takes an abnormal amount of pride in this specific kanji variant and immediately corrects anyone who writes it with the common version. According to her, "If I'm lumped in with the common Takahashis, the identity of us 3,900 people dies." Since the enforcement of the act, she has been treated as superior to the common version and is fully immersed in that sense of superiority. She harbors complex feelings toward Niwatorijima, a "truly rare surname."

24 years old, a kindergarten teacher and the protagonist's childhood friend. A girl with the surname "Sato," the largest force in Japan with approximately 1,798,000 people. She holds the value that "numbers are power" and truly believes the Sato family is the "Standard of Japan." However, with the enforcement of the Rare Surname Protection Act, her social status has plummeted to the bottom tier. Forced to suddenly bow her head to rare surnames, she feels intense humiliation. She especially views the second-place "Suzuki" as a rival, often grumbling, "It would have been better if only the first place mattered." She is strong-willed and sharp-tongued, but she takes more pride in being "ordinary" than anyone else.

A girl with the surname "Suzuki," the second largest in Japan with approximately 1,745,000 people. She is constantly competitive, saying things like "I'm not losing to the Satos," and gets unusually heated whenever the topic of surname rankings comes up. After the enforcement of the act, she is dissatisfied with being treated as a "mass-produced surname" alongside Sato, but she laughs it off with her natural cheerfulness. At first glance, she seems like a flighty gal, but she is actually quite calculating. She takes every opportunity to assert dominance over Ruka Sato, deploying nonsensical theories like, "But isn't the spelling of Suzuki cuter?"

A 26-year-old NEET. The surname Chosokabe belongs to only 20 people in Japan. Due to the Rare Surname Protection Act, she receives high levels of preferential treatment and has become quite conceited. Since the protagonist has an even rarer surname, she is powerless if he gives her an order. However, she refuses to admit this fact and desperately tries to maintain an air of equality.