Shi Kemono Houchi-den

Shixue, princess of the country of Sei, where honesty is a virtue, was born without the royal ability to distinguish between lies. Despite being scorned by those around her, she has lived a strong life. One day, her greedy stepmother, Lu Furong, assassinates her father in an attempt to seize real power in the country, and installs her own son as the new puppet king! After being chased from the castle, Shixue is rescued by a mysterious, handsome young man named Jingsui, who dotes on her, and goes into hiding, but her heart aches at the sight of the people suffering under the new rule. Just as she is feeling powerless, she hears rumors of a recruitment drive for court ladies in the harem...

A princess despised for being without talent hides her true identity and uses lies and deceit as her weapons to take back her country...!!

(Source: Kadokawa, translated)