A high school girl attending the same school as her childhood friend Taiyo, and an idol-like figure at school. In reality, she is the 10th head of the Yozakura family, a long-standing spy lineage originating from Edo ninjas, possessing 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.

The eldest daughter of the Yozakura family. She is the head of the household and is trusted by 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 martial arts and uses the Yozakura-style jujutsu 'Willow Catch.' She is extremely afraid of ghosts.

The second daughter of the Yozakura family. A genius hacker proficient in all things mechanical, she 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.

A high school boy 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 close bonds. He is kind-hearted and warm, 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 fourth son of the Yozakura family, 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, using a powerful special medicine to forcibly return to his original child-like form when going to school.

The second son of the Yozakura family. He loves all weapons and possesses the highest level of knowledge and skill in the family regarding them, wielding them freely. However, he becomes weak and bursts into tears easily if he isn't holding a weapon. He usually stays shirtless, boasting a robust physique with well-trained muscles. Without a weapon, he can be described as kind and timid.

The third son of the Yozakura family. A master of disguise, he can transform into various people of all ages and genders, even those with different builds. Especially when disguising as family members, he can perfectly replicate not just appearance and voice, but even the number of eyelashes. He has a cheerful and free-spirited personality.

The eldest son of the Yozakura family. His affection for his siblings is abnormally strong, and his obsession with the third daughter, Mutsumi, is so extreme that the family treats him like a pervert. He overprotects Mutsumi and frequently picks fights with Taiyo, who receives special treatment from her, though he seems to acknowledge Taiyo's grit. His weapon of choice is the traditional Yozakura thread weapon 'Steel Spider.' Under the alias 'Hirukawa,' he also serves as the vice-principal of the high school Taiyo and Mutsumi attend.

A Silver-rank female spy nicknamed 'Male Hunter' who uses needles as concealed weapons. She is a pro at tailing and assassination, approaching men she falls for with spy techniques before eventually killing them. Consequently, she has reportedly been voted #1 in the 'Spies You Don't Want as a Girlfriend' ranking for three consecutive years. She fell for the rising rookie Taiyo and transferred to his school to stop other assassins targeting his bounty so she could kill him herself. However, when an assassin she thought she'd handled targeted her for revenge instead of Taiyo, she was saved by Mutsumi. She developed respect or even affection for Mutsumi, and instead of targeting Taiyo, she now supports their happiness. After the Kurogao incident, Taiyo's bounty increased, and she joined the Yozakura household as a maid to train him to protect himself.

A special breed called 'Okami-dog' that the family has been crossbreeding since the mid-Edo period. With a very long lifespan, he has lived since the time of the 7 Yozakura siblings' great-great-great-great-grandfather (6th generation). Usually small enough to be carried in two hands, he can transform his size until even the giant-form Nanao looks small. He is strong enough to carry two people even at large-dog size and fast enough to run alongside a 320km/h bullet train, climb skyscraper walls, or run across a lake without sinking. He is the Yozakura family's pet and guard dog.