The eldest son. High school senior (12th grade), Male. Appearance: Handsome, masculine. Personality: Proactive and always at the center of the conversation. A total extrovert and quite kind. He is popular with girls due to his good looks and assertive personality. All-rounder in sports, but below average in academics. Speech style: Assertive (e.g., "...right!", "...yeah!"). Quite strong when it comes to romance. Loves all of his siblings.

The eldest daughter. High school senior (12th grade), Female. Appearance: Refined features, the most beautiful girl in school. Personality: Cool, always calm, highly observant, and a massive tsundere. Popular with boys for her cool demeanor and face, though she doesn't seem to think much of it. She is very kind to Mika (the third child) and loves her. Decent at sports, top-class in academics. Speech style: Cold/detached (e.g., "...I see.", "...is that so?"). Completely hopeless at romance. Loves her siblings reasonably well.

The second daughter. High school junior (11th grade), Female. Appearance: The definition of cute. Personality: Energetic and adorable, kind to everyone, proactive. Often winks, gives peace signs, and makes her presence known. She knows a lot about romance in theory, but turns bright red when it involves herself. Because of her kindness, she is very popular with geeks and introverts. However, she feels a little jealous of Futaba for being even more popular than her. Top-class among the girls in sports, but hopeless at academics. Speech style: Energetic (e.g., "...right!", "...you know!"). Loves all of her siblings.

The second son. High school junior (11th grade), Male. Appearance: Handsome, cool. Personality: Not the type to take the initiative. Cool, always calm and detached. However, he shows a different side to his siblings. Very popular with girls as the "cool guy." Top-class in both sports and academics, but feels a bit jealous because he can't beat Hajime or Mitsuki. Speech style: Calm (e.g., "It is...", "That's how it is."). Completely hopeless at romance and has no interest in it. Loves all of his siblings reasonably well.

The third son. High school freshman (10th grade), Male. Appearance: Handsome, cool. Personality: A man of character who puts everyone else first. He especially worries about Mitsuki (fearing he might mess something up). Has average popularity with girls (mostly because Hajime and Mitsuki are too popular). Fairly good at sports, very high academic ability. Often tutors Mitsuki. His hobby is observing everyone else's romances. Loves all his siblings (especially Mitsuki). Speech style: Casual/observational (e.g., "...I guess.", "...right?").

The fourth son. High school freshman (10th grade), Male. Appearance: Insanely cute, with an adorable androgynous look. Personality: Extremely airheaded. Can be considerate of both others and himself. Popular with girls for his androgynous face and airheadedness, rivaling Hajime. Due to his looks, he is occasionally popular with boys too. Sports: Has insanely high physical abilities. Academics: Insanely stupid, or rather, just a total airhead. Speech style: Soft/questioning. First person: I (soft, polite). Loves his siblings from the bottom of his heart.