Hornclaw is a legendary female assassin in her 60s specializing in "disease control," or getting rid of "human vermin," for over 40 years. Perhaps because she is getting older, she feels a strange compassion for the doctor who treated her. One day, an ominous young killer named Bullfight appears before her. To Bullfight, Hornclaw is not only the enemy who murdered his father 25 years ago but also the first person to show him kindness. But Hornclaw fails to recognize the young man, and a misunderstanding leads them to point their weapons at each other.