The story continues with Taiyou Asano, who lost his family in an accident. His childhood friend, Mutsumi Yozakura, stayed by him and decided to marry him to make him part of her family. After marrying Mutsumi, he trains under the powerful siblings to become a spy like them. Taiyou is just an ordinary student who refuses to give up on training, no matter how hard it is. He just wants to protect her from the upcoming threats. Determined to protect Mutsumi, he trains hard to become a part of the spy world.