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! The Yozakura siblings take a trip to the ominous and decaying Yozakura Residence, which is said to be haunted! There they are confronted by the second head of the Yozakura family, Lady Ninomae. But she's supposed to be long dead, so what does it mean?!