Tsuihou sareta Renkinjutsushi wa Mujikaku ni Densetsu to Naru: Yandere Imouto (Oukoku no Shugoryuu) to Issho ni Henkyou de Shiawase ni Kurashimasu!

Mys, the eldest son of Duke Windsor, finds himself at the center of a kingdom-shaking controversy when he is suddenly exiled to the borderlands by royal decree. The official charge: treasonous intentions during a clandestine visit to Valitra, the mighty dragon that has long served as the kingdom's protector. As Mys establishes his new life in the harsh border territories, his mastery of alchemy begins to transform the region in remarkable ways, bringing prosperity to those who had been forgotten by the capital. Yet beneath the surface of these developments, ancient bonds and hidden truths threaten to reshape the very foundations of the realm. With tensions rising between the crown and its most powerful guardian, the kingdom stands on the precipice of unprecedented change. In this tale of exile, redemption, and the price of power, the fate of nations may ultimately rest in the hands of those who have been cast aside.