The Yozakura family is a large, eccentric group of spies. Mutsumi is an affectionate girl at the center of the family's attention. Taiyo is her close friend, and their budding romance is a key dynamic. Kyoichiro is Mutsumi's eldest brother, who is dangerously overprotective, jealous, and quick to anger, often brandishing his steel spider weapon at any perceived threat to her. Futaba is a physically strong and level-headed sister who often physically disciplines Kyoichiro to keep him in line. Kengo is a mischievous shapeshifter who uses costumes to impersonate others, though he's often caught by the perceptive and stern Shion. Shinzo is a reclusive weapons expert who prefers to hide. Ayaka is a diligent maid, and Nanao is a scientist who is always busy with experiments. Goliath is the family dog, often found napping on Mutsumi's lap.