The eldest son of the Yozakura family. He possesses top-tier popularity and skill. His affection for his siblings is abnormally strong, especially toward the third daughter, Mutsumi, which borders on extreme obsession, leading the family to treat him like a pervert and a foolish eldest brother. While he overprotects Mutsumi and frequently picks fights with Taiyo for receiving special treatment from her, he seems to acknowledge Taiyo's grit. His weapon of choice is the "Steel Spider," a thread-based weapon passed down through the Yozakura family. He serves as the vice-principal of the high school Taiyo and Mutsumi attend under the alias 'Hirukawa'.

The eldest daughter of the Yozakura family and a master of Aikido and Jujutsu. She is the pillar of the household, acting as the head of the family and earning the trust of her younger siblings. Despite her age, she has a very small build and a youthful face. She loves Gothic Lolita fashion and is always seen wearing it. She excels in physical techniques and uses the Yozakura-style Jujutsu "Willow Catch." She is extremely afraid of ghosts. Standing at 134cm, she is technologically illiterate, cannot handle alcohol, and loses control of her superhuman strength when drunk. If she can't fix a machine, she sulks, and if she sees a ghost, she wraps herself in a blanket all day like a child.

The second son of the Yozakura family and a specialist in weaponry. He loves all weapons and possesses the highest level of knowledge and skill in the family regarding them, handling any weapon with ease. However, he becomes weak and bursts into tears the moment he is not holding a weapon. He usually stays shirtless, boasting a well-trained, muscular physique. He lives inside the "Trash Can Tank No. 3," which is loaded with all sorts of built-in weapons.

The second daughter of the Yozakura family and a genius hacker/gamer. She is a prodigy proficient in all things mechanical and manages the family's various machines and equipment. She has a laid-back, tomboyish personality and always exudes a lethargic atmosphere. As a gamer, her motto is to enjoy even the worst games with all her might. She is the character in charge of sex appeal; starting with her large chest, her collarbone area is usually the most exposed.

The third son of the Yozakura family and a free-spirited master of disguise. As a master of disguise, he can transform into various people regardless of age or gender, even those with different physiques. When disguising himself as a family member, he can perfectly replicate not just their appearance and voice, but even the number of their eyelashes. He has a cheerful and free-spirited personality.

The 10th head of the Yozakura family. A high school girl attending the same school as her childhood friend Taiyo, she is like the school's idol. As the third daughter and the 10th head, she possesses overwhelming charisma. Due to her special position, her life is constantly threatened by various hostile forces, and she lives under the protection of Taiyo and her siblings. It is said she developed various hobbies because she had to spend so much time in her room. She is such a terrible singer that everyone in the family except the siscon Kyoichiro is horrified; birds have been known to faint and fall from the sky upon hearing her sing.

The fourth son of the Yozakura family, specialized in medicine in addition to superhuman strength. He is in charge of the family's medical team. Through his special ability 'Immunity,' he can adapt to poisons or enhance his body, but control is very difficult. He attends the same high school as Taiyo and Mutsumi, and when going to school, he uses a powerful special medicine to forcibly return to his original child-like form. He is affectionate toward his family.

A boy who became the son-in-law of a spy family. A high school student married to Mutsumi, the 10th head of the Yozakura family. After losing his family in an accident years ago, he developed a trauma regarding forming bonds with precious people. He is compassionate and warm-hearted, often prioritizing others over himself. After learning Mutsumi's true identity, he entered the Yozakura family as a son-in-law to protect her. He holds a strong conviction to protect what is precious to him and aims to become a full-fledged spy to live as a member of the Yozakura family.

The pet and guard dog of the Yozakura family. Usually small enough to be carried in two hands, he can transform his size to the point where even the giant Nanao looks small. He is strong enough to carry two people even when transformed to the size of a large dog, and he is fast enough to run alongside a high-speed train at 320 km/h, climb the walls of skyscrapers, or run across the surface of a lake without sinking. He has served only the family heads for generations and gets along reasonably well with other family members, but even Goliath avoids Kyoichiro.