According to 'Sogamonogatari,' she was named Mitora (three tigers) Gozen because she was born on the time, day, and year of Tiger, she was actually born in the year of the Sheep.
寅年の寅の日の寅の刻に生まれたので三寅御前と名づけたと「曽我物語」にあるが、実際は虎女は未（ひつじ）年の生まれである。