One Piece: Unreal Adventure - Chapter 17: This is Going To Be A Long Day

Mythical Abode Mountain, Cloud’s End Cliff, the most dangerous of Azure Cloud Continent’s four deadly areas. Cloud’s End Cliff’s base is known as the Grim Reaper’s Cemetery.

Fate and destiny; no one can foreshadow the terrifying challenges on the road to the Pure Land. Instead, one may unearth the evil within the road of light towards paradise.

A King’s Holy Sword, bringing light to the darkness,

An unyielding soul, igniting the fiery hope of the world,

As his soul awakens, the youth fiercely battles the gods of darkness and evil,

As the surging dark clouds gushed out like a phantom, their conflict swept the world like raging tide!

The clash of darkness and light, a massive war on the verge of exploding,

The decisive battle of gods and deities rewrite the creation of the world into one destructive epic!

- Description from Novelupdates

Cha Myung-jun, a sergeant who neared the end of his military service, found himself confined in the Ministry of National Defense’s bas**ent for over three decades due to his newly awakened abilities, just before the outbreak of war. Spending thirty years as the world’s most formidable blacksmith, wielding nothing but hammers, he skillfully outwits the watchful eyes of the Ministry of Defense to serve the war effort and reset the course of time. Now given a second chance at life, can he lead a successful campaign to avert humanity’s downfall and secure its salvation?

The story starts on earth, after some unknown circumstances, the world was suddenly invaded by monsters from other worlds. Many died and even more turned into zombies, starting what many would call 'The apocalypse Era'.

Rin, a normal teenage boy who lost all of his family members was on the verge of falling into despair when a goddess appeared and sent him to another world that was very similar to a game Rin played before the apocalypse.

Her goal from this was simple, trample on all the protagonists and become the strongest creature in that world for a chance to get back what he thought he lost forever.

Accompanied by a cold beauty, both of them embark on a new journey to become stronger, get back to their world and fix everything.