Taiyo Asano has been on his own ever since his parents died. 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!

Searching for Mutsumi's father, Momo Yozakura, Taiyo infiltrates an excursion steamer connected to Tanpopo. For all his work, he finds no clues. The disappointing failure of a mission changes into an enchanting encounter when he meets a beautiful young woman on the train. But she is no ordinary girl...she is White Snake and a member of the Hazakura battalion!