Romance! A crazy, overprotective brother! And...spies?!Taiyo Asano has been on his own ever since his parents died and the only one who seems to care for him is his childhood friend and classmate, Mutsumi Yozakura. But Mutsumi has a secret—she is the head of a family of spies! And on top of that, her brother Kyoichiro is dangerously protective of her! To stop Kyoichiro from killing him, Taiyo and Mutsumi must take the ultimate leap—marriage! Because in the Yozakura family, family cannot kill family.Kyoichiro, Hifumi, and Alpha head to the North Pole! On an uninhabited island, they finally find Nanao, stuck inside one of Dr. Mozu’s labs. Kyoichiro declares the lab to be the “Nanao Dungeon” and gives Hifumi and Alpha a quest to rescue “Princess Nanao”!