The Crown of Rutile Quartz

Slaine spends his days living as a humble commoner in the quiet Kingdom of Hasenvalia—until the royal family is wiped out in a palace fire.

In the aftermath, Slaine discovers a secret kept from him all his life: He's the king's illegitimate son and now the sole surviving heir to the throne! Thrust into power with no training and precious few allies, Slaine must navigate court politics, earn the trust of wary nobles, and learn how to rule a kingdom he never thought would be his.

With his sharp-witted and fiercely loyal aide-de-camp Monica at his side, Slaine begins to grow into his role. But not everyone is pleased to see a commoner rising to the top. While some welcome the new king with cautious hope, others hide their true intentions behind polite smiles. As threats lurk in the shadows, young Slaine must rise to the challenge—or risk losing the crown before he ever gets to wear it.

(Source: J-Novel Club)