All the People Are Trying to Open up Wasteland in Another World, but I Am Opening up the Sky with One Sword

On the day he was drawn into the chaotic alien world, there were only two sounds left in the world - the roaring beasts and the desperate cries. The rules here are simple, the weak eat the strong. Some people clutched the broken spears and trembled, while others hid in the cracks and survived, praying to God and the savior. But there is no savior in this world, no fraternal god. Until he held a sword.