I Sense Trouble

My father, a master swordsman, had wanted a son; Fate snickered and gave him a daughter. Still, he felt I should know how to protect myself should I ever find myself in danger. When he finished training me, he looked at me and said, "Daughter, you now know how to defend yourself. You need not fear any man who wishes you harm." This evening, I heard a noise. I loosened my yukata, gripped my katana, and waited...