 Code Age Commanders is set in an " <unk> world " ( <unk> , <unk> sekai ) , a fictional hollow world similar to a Dyson sphere , with people living on its internal surface . The center of the sphere is occupied by the " Central Code " , a spherical structure which goes through a transformation called " Reborn " about every ten thousand years , destroying all life on the globe and allowing for the birth of a new one . 
