Oda Nobunaga to Iu Nazo no Shokugyou ga Mahou Kenshi yori Cheat datta node, Oukoku wo Tsukuru Koto ni Shimashita

In this world, on the day that they reach adulthood, everyone visits the temple to receive their life's calling. Many will become warriors or magic users. But when the frail younger brother of a minor feudal lord named Arsrod goes in for his job, he comes out with...Oda Nobunaga?! Not only has that job never been heard of, not a single person can even figure out what it's supposed to mean. But when this young man inherits the experience, tactics, and prowess in war of the great Sengoku strategist Nobunaga, his very destiny will change!

(Source: Yen Press)