Ouji-sama no Wakeari Kaikeishi

Colette is an accountant working in the royal capital's commoner tax department. She's been demoted by her boss and ends up becoming the personal accountant for Prince Radis, who is rumored to be misanthropic! She reluctantly accepts the position for a limited period, but the prince, with a devilish smile on his face, tells her that he's searching for a child who sneaked into the castle ten years ago.

Is that me? Surely, if I'm found out, I'll be executed!? I don't want to die, so I'll quit my job as the prince's accountant before he finds out!!

(Source: Ichijinsha, translated)