Herscherik R: The Epic of the Reincarnated Prince

The day before 35-year old otaku lady Ryouko Hayakawa's birthday, met her end in this world by way of a traffic accident――――or at least, she was supposed to. But when she opened her eyes, she found a fantasy world. She reincarnated as blond-haired, blue-eyed seventh prince, Herscherik! Fully enjoying a leisurely prince life free from wordly 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, to save the country Herscherik relies on the "office worker" skills and "conman ability" from their previous life, and now takes action!

The life of Ryoko Hayakawa, a hard-core otaku, came to an abrupt end the day before her 35th birthday, before she was reincarnated as a beautiful prince in a fantasy world. However, her dream-like royal life didn’t last long, as she soon uncovered the depths of politics and corruption of her kingdom. To protect the king and his people, Ryoko, reincarnated as Prince Herscherik, resolved to conquer the darkness within his country. The problem was, the prince had no physical strength or magical powers, and even his stunning looks were surpassed by every other member of the royal family. Still, the prince persevered, using the skills he acquired during his previous life—the experience of an office worker, Ryoko’s drive for change, and her otaku brain.

Books in this series:
I. The Reincarnated Prince and the Kingdom in Woe
II. The Reincarnated Prince and the Twilight Knight
III. The Reincarnated Prince and the Haloed Sage
IV. The Reincarnated Prince and the Hero of Light
V. The Reincarnated Prince and Felvolk's Greatest Treasure

(Source: J-Novel Club)