A Mysterious Job Called Oda Nobunaga, Vol. 1 (light novel) — Kisetsu Morita

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!