The God Hachiman of Rhozgelia

From across time, space and our universe itself, something pulled Hachiman away from his world, something powerful that needed his help. He wakes up in an unfamiliar room, naked and with no memory. A woman enters, saying things such as Gods and Divines, a terrible war between factions, the Black Void, his alternate selves, his duty as a Patron God and that he is her God and Master.