I Was Invited to a Nation as a Warrior from Another World, But I Declined and Decided to Start as a Soldier

Yukiichi Tozuka, who was attending high school in peaceful Japan, suddenly gets caught up in a class summoning as a warrior from another world during school break. In the summoned other world, he is promised a guaranteed life if he becomes a warrior to save the world, but Tozuka finds the unusually good treatment strange. Due to the words and actions of his classmates and a mysterious voice he sometimes hears in his head, he chooses to abandon life in the castle and take the path of a soldier.