Uchi no Seijo-sama wa Haragurosugi Darou.

is a Japanese light novel series written by Yu Ueno, with illustrations by Richu. The series began publication on December 10, 2017 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
Earn a national budget for the Black Saint !?

The work of a soft-boiled knight (!?) Fantasy!

Kai, who wants to be a fallen knight, was adopted in the remote country of Braufalt. Kai dances in this land, which is governed by a pure saint for generations, saying, "You can become a knight of a saint!" However, what was waiting there was Princess Flora, who looks like an angel and is a devilish "Black Saint" !?

"Your job is to make money. Earn extra pocket money!"

Kai runs for money at Flora's command. However, it is an unreasonable storm, such as hunting a flying dragon to get a fang to make a special product, or looking for a hot spring to make a tourist spot.

Princess Love Life! Lillie is also troublesome, can Kai really become a long- sought knight !? The work (!?) Fantasy of the Black Saint and the soft-boiled knight begins !