He is a Navy Admiral, praised by the world as the dawn that pierces the gloom: the Holy Lance, Longinus.
He is the king of the underworld, feared by the world as the darkness that will bring an era to an end: the Demon Sword, Apophis.
He walks between light and darkness, weaving a battle hymn of blood and fire.
When he finally looks back, he finds the world beneath his feet.
PS1: This book has no Devil Fruits and no System. The title has nothing to do with the Dark-Dark Fruit!
PS2: The timeline is long, beginning on the day Roger ushered in the Great Pirate Era!
PS3: The protagonist is no good-for-nothing. The story is highly satisfying and leans toward lighthearted wish fulfillment, but the characters should generally be intelligent!