The Epic Tale of the Reincarnated Prince Herscherik(2016)

Herscherik

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)