Mission: Yozakura Family Vol 3

Mission: Yozakura Family by Hitsuji Gondaira. An Action manga rated Teen, published in English by Viz Media.

Shy high schooler Taiyo Asano's only friend is his childhood friend Mutsumi, who happens to be the head of a family of elite spies. To protect her from her overprotective brother, Taiyo marries into the family, and now he has to learn how to survive as a Yozakura.