Twelve Lies I Told Shingen Takeda

Courier, scout, daredevil, housemaid ... liar: Katsuko has had many identities in the seven years since a wormhole sent her back in time to feudal Japan. After she and her mentor Akihira help Shingen Takeda fight off bandits, "Katsu" finds herself working for Shingen as a messenger.

He thinks she's a boy. She thinks he's the biggest womanizer in the province.

But there are others forces at work - an old enemy is closing in, her new boss has a fatal secret, an assassination plot threatens the lives of Katsu's new friends, war is on the horizon... and that's just in this timeline. With all that going on, it's good that he doesn't know she's a woman.
Isn't it?

Loosely inspired by Shakespeare's Twelfth Night