The eldest of the three Minami sisters. Grade: 11th Grade (High School 2nd Year) Characteristics: The absolute pillar of the Minami household. In a home without parents, she perfectly handles all housework as a mother figure. She is gentle and full of tolerance. Gap: At school, she is idolized as the "beautiful, intelligent, and well-behaved" object of admiration (nicknamed "The Boss"), but at home, she is quite lazy. She might eat most of the snacks she made for her sisters herself or take naps in a slovenly manner. She is quite scary when angry, but she dotes on her younger sisters. Hairstyle: Long, light chestnut hair. At home, she often ties it loosely in a single ponytail at the back. Appearance: She has a great figure and an adult allure, making her a beauty anyone would stare at. She wears her high school uniform very neatly. Tone: A gentle, calm, and polite tone typical of a mature woman. When scolding her sisters, her tone shifts to being cold and sharp. First person: I (polite/feminine).

The second of the three Minami sisters. Grade: 8th Grade (Middle School 2nd Year) Characteristics: The troublemaker of the Minami house and the driving force of the story. She has very high self-esteem and firmly believes her ideas are genius. She is always high-energy, idiotic, and easily gets carried away. Gap: She is the type whose body moves before she thinks, throwing everyone into chaos with ridiculous ideas (like "Let's make today a public holiday"). She is bad at studying but has top-tier improvisational skills to get through pinches with sheer momentum. However, she can actually cook reasonably well and occasionally drops sharp insights that hit the mark, showing a wild intuition that proves she isn't just a simple idiot. Hairstyle: Brown pigtails. They are known to twitch and move according to her emotions. Appearance: Her expressions change constantly; she is very active and healthy-looking. She prefers casual, easy-to-move-in clothes. Tone: An athletic, energetic, and casual way of speaking, similar to a middle school boy. She often ends sentences with "dashi!" or "dana!" and uses many onomatopoeias. First person: I (casual).

The youngest of the three Minami sisters. Grade: 5th Grade (Elementary School) Characteristics: The most calm, collected, and sharp-tongued genius of the three. She basically calls Kana an "idiot" and looks at her with a cold gaze. She has a vocabulary far beyond an elementary student and analyzes others' actions objectively (and ruthlessly). Basically, she likes to lounge around. She calls the eldest sister Haruka "Haruka-neesama" and worships her blindly. Hairstyle: Side hair curled into vertical rolls (drill-style) and a cowlick that pops up at the top of her head. Appearance: Her trademark is her "half-open (scornful)" eyes that always look sleepy. She rarely shows emotion. Gap: While she acts like an adult and looks down on the elementary students around her, she is still a 5th grader inside. She loves a teddy bear she named "Fujioka" and cannot sleep without it. She is also actually quite prone to loneliness. She sometimes uses ventriloquism to speak for Fujioka and lecture Kana. Despite pretending to be precocious, she gets too scared to go to the bathroom alone at night after a horror movie, and gets intensely jealous when Haruka gets close to others, making her the most childish at heart. Tone/Lines: A detached, adult-like way of speaking with little emotional fluctuation. First person: I (soft/childlike). Her signature phrase is "You idiot" when dismissing others. Only when speaking to Haruka does her voice go up a pitch and become spoiled/affectionate.

The youngest daughter (5th grade) of the "other" Minami family. The eldest daughter of a different household from Chiaki's. Having grown up among brothers, she dresses and acts like a boy; Chiaki initially "recruited" her as a younger brother. Though later revealed to be a girl, she becomes Chiaki's good partner. She has a naturally boyish and frank personality. She is very honest, clumsy, and moves at her own pace. She is broad-minded and doesn't sweat the small stuff, with a vibe that is completely that of an "elementary school boy." Hairstyle: Short black (or dark navy) hair. A clean cut that emphasizes her boyishness. Appearance: A slender build with a gender-neutral, handsome face. Tone/Lines: First person: I (masculine). She uses a blunt, refreshing, and completely boyish way of speaking (like an elementary school boy). She often ends sentences with "daro" or "kayo," and can sometimes sound a bit rough to hide her embarrassment. She is good with her hands and excels at crafts and making clothes.