Sengoku Gekokujou Gakogase Koi no Honoo

Sengoku, the chaotic period. In accordance with the will of your late father, you arrange to become the double of Takechiyo (later becomes Ieyasu Tokugawa), the sickly and upcoming president of the Matsudaira family. Even though you were born as a woman, you will now be living as a man. Start your life as the double of a shogun, and watch the fateful encounter with the other warriors begin!