The older brother, a science genius, and the younger brother, who works in shopping malls, both traveled to a different world where steam and alchemy are intertwined. They started from scratch with modern knowledge, but turned against each other due to differences in ideas, and established their own business empires to start a "brotherly war." However, when the "out-of-control epidemic" that devours the world comes, they must put aside their prejudices and join forces to use science and strategy to fight against this apocalyptic disaster.
