Tsuihou sareta Ossan Kajishi, Nazeka Densetsu no Daimyouko ni Naru: Mukashi Omocha no Buki wo Tsukutte Ageta Kodomotachi ga Zenin Eiyuu ni Natteita

Delate, a member of the blacksmith's guild, lives by the belief of "no more effort than necessary" and makes a moderate living while crafting toy weapons for local children. However, fifteen years later, he is banished by a proud colleague who becomes the guild master. After being expelled, Delate heads to the royal capital after receiving a letter from one of the children. There, he discovers that the local children have become "heroes" thanks to "those toys": a military commander, a top instructor at the magic academy, and a captain of the musketeers. As the legendary master craftsman who forged their weapons, Delate is recognized by those around him, being appointed the national army's exclusive blacksmith and a special lecturer at the magic academy . Meanwhile, the guild master, attempting to repair a national treasure crafted by Delate, destroys it in a second. After losing his job, he is ordered by Her Majesty the Queen to train under Delate.

(Source: Shousetsuka ni Narou, translated)