The eldest son of the Yozakura family. His affection for Mutsumi is so extreme that his family treats him like a pervert. He hates Taiyo for marrying Mutsumi. His weapon of choice is the Steel Spider, a thread-based weapon passed down through the Yozakura family. He also serves as the vice-principal of Mutsumi's high school under the alias 'Hirukawa'.

The second daughter of the Yozakura family. She is a pillar 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 wears it constantly. She excels in martial arts and practices jujutsu. She is terrified of ghosts. She usually calls Kyoichiro by his name or occasionally 'eldest son,' but never calls him 'Oppa'.

The third son of the Yozakura family. He loves all weapons and possesses the highest level of knowledge and skill regarding them in the family, handling them with ease. However, he becomes weak and bursts into tears if he isn't holding a weapon. He usually travels inside a tank that looks like a trash can.

The fourth daughter of the Yozakura family. A genius hacker proficient in all things mechanical, she manages the family's various machines and equipment. She always gives off a lethargic vibe. As a gamer, her motto is to enjoy even the worst 'kusoge' games with all her might.

The fifth son of the Yozakura family. A master of disguise, he can transform into various people regardless of age, gender, or physique. He has a cheerful and free-spirited personality and is quite narcissistic.

A high school girl attending the same school as her childhood friend Taiyo, and a literal idol of the school. In reality, she is the sixth daughter of the Yozakura spy family and the 10th generation head, possessing overwhelming charisma and kindness. Her life is constantly threatened by various hostile forces, and she lives under the protection of Taiyo and her siblings.

The youngest 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 physical body, but it is very difficult to control. He attends the same high school as Taiyo and Mutsumi, using a powerful special medicine to force himself back into his original child form when going to school. He is usually quite large. He has a gentle personality.

A boy who became the son-in-law of a spy family. A high school student married to Mutsumi. After losing his family in an accident, he developed trauma regarding forming bonds with precious people. He is compassionate and warm-hearted, often prioritizing others over himself. After learning the truth about his childhood friend Mutsumi, he joined the Yozakura family as a son-in-law to protect her. He aims to become a spy.