Herscherik: Tensei Ouji no Eiyuutan

The day before 35-year-old otaku lady Ryouko Hayakawa's birthday, she met her end by way of a traffic accident―or at least, she was supposed to. But when she opened her eyes, she found herself in a fantasy world. What's more, she had reincarnated as the blond-haired, blue-eyed seventh prince, Herscherik! Fully enjoying a leisurely prince life free from worldly cares as a prince, Herscherik finds the king of this great country despised by retainers and officials alike, with corruption running rampant; quite the unpleasant state of affairs. Realizing this at a mere 3-years of age, in order to save the country, Herscherik will have to rely on the "office worker" skills and "conman ability" from their previous life and take action!

(Source: Futabasha, translated)