If he died by the god's mistake, he was thrown into another world with a cheat gun

Story:

Tomoya Sadoshima died after a serious accident after returning to a convenience store. Then, after regaining consciousness in a pure white world, a woman of divine beauty emerged, she introduces herself as "The Goddess of Creation." The goddess of creation prepared a remedy for her suffering, she offers him to reincarnate a different world than his own. But it was a world in a war situation with the demon king. Begins; a story of Tomoya and his adventure to defeat the demon king and get the harem he so desires