Legend of a Cowboy in Another World

Our story starts in a familiar place, at a familiar time, under familiar circumstances:

After being involved in a tragic car accident on the streets of Tokyo, and briefly meeting a mysterious goddess, an unwitting hero finds himself in over his head, awakening in a world of magic and wonder with a simple task before him - reach the lands of darkness and do battle with the demon lord who dwells there.

But before the adventure can begin, a well-meaning stranger intervenes; a new hero arrives, and the strings of fate begin to unravel.