Yuusha Shoukan ni Makikomareta kedo, Isekai wa Heiwa deshita

Caught up in a Hero Summoning, a young man finds himself in another world—but he is not the Hero; someone else has been summoned for that role. Expecting to be swept into a familiar tale of war, he instead discovers a peaceful land where the Demon Lord was defeated a thousand years ago, the races live on friendly terms, and there has been no war for a long time. With a safe return to Earth planned after a year, he intends to enjoy his stay, travel, and attend a festival held only once every few decades. But as he settles into this calm world, influential figures keep gathering around him, complicating his hope for a quiet visit.