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 finally manage to track down the missing Kyoichiro. Taiyo rushes to join them, but something is clearly wrong with the eldest brother! Infected by the Yozakura family First Head's poison, his body is sprouting poisonous cherry blossoms. The siblings spring into action to save their slightly annoying but beloved brother!