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. Tsubomi Yozakura comes to Taiyo in his dreams, asking him to kill her! She tells him that, in order to do it, he'll need two things. Following her instructions, Taiyo decides to take on the silver-rank spy advancement exam. Unfortunately for him, the test proctors are all Yozakura siblings.!.