Katainaka no Ossan, Kensei ni Naru ~Tada no Inaka no Kenjutsu Shihan datta no ni, Taiseishita Deshi-tachi ga Ore wo Hottekurenai Ken~

In a quiet rural village, Beryl Gardenant runs a modest fencing dojo, far from the grand ambitions of his youth. Once a swordsman with lofty dreams, he now humbly refers to himself as a “worthless old man,” resigned to a peaceful, uneventful life. “Maybe this slow, simple existence is all that’s left for me,” he muses. But fate has other plans when Aleutia, a former student now serving as a royal knight, arrives with an unexpected offer: “I’ve nominated you as the exclusive instructor for the royal knights.” Beryl, bewildered, finds himself dragged to the capital, where he reunites with past students—legendary figures like the top adventurer and an S-class mage—all pleading for his guidance once more. “Surely you’ve outgrown me by now,” he insists, downplaying his own skills. Yet his decades-honed swordsmanship earns him fame across the kingdom, where whispers of the “Countryside Sword Saint” spread like wildfire. “THAT NAME IS SO EMBARRASSING!” he protests. This is the tale of an overlooked master, finally receiving the recognition he deserves—a lighthearted fantasy about an unlikely middle-aged hero rising to prominence.

(Note: The rewritten version maintains the original tone, expands on details, and ensures high uniqueness while staying true to the story’s essence.)