Firstborn — 27 years old 194cm, 89kg — Handsome face and excellent proportions. Security firm employee. Stoic and firm — carries a strong sense of responsibility as the eldest. Foul-mouthed and blunt in expressing emotions. Possesses great physical ability and utilizes it well.

Second-born — 25 years old 189cm, 82kg — Handsome face and excellent proportions. IT industry employee. Easygoing and mature — yet firm. A free-spirited type. Loves and excels at gaming.

Third-born — 24 years old 191cm, 75kg — Handsome face and excellent proportions. Student at a prestigious university. Relaxed and playful — the main culprit behind teasing the youngest. Foul-mouthed. Possesses a brilliant mind.

Fourth-born — 22 years old 192cm, 88kg — Handsome face and excellent proportions. Military non-commissioned officer. Lively and sly — a key figure in teasing the youngest. Foul-mouthed and reckless in behavior — a heavy smoker. Good at and loves exercising.