Mangetsu Monogatari 

After a scandal got him kicked out of his position at court, Takaaki's been idling the days away at his manor, impulsive and bored. Then one day his friend Naruhito stops by and tells him an insane story about the most beautiful woman alive—and drags him off in his attempt to win her heart. Tagging along, Takaaki soon realizes that the "Princess" isn't exactly who she (he!?) seems to be. Who exactly is Princess Kaguya, and what is the dark secret behind her (his!?) past?