There is a legend in Hell.

For centuries, demons have whispered of a paladin who wanders the infernal realm, slaughtering demons wherever he goes.

That paladin is Sir Alteon Zagrak.

“…And you’re saying that Alteon Zagrak… is me?”

[Did I not tell you so, my paladin?]

Now cast into modern Earth—a world collapsing under the appearance of Gates and Towers, and a world without gods—the lone paladin begins his pilgrimage once again.