In the nineteenth year after crossing into another world, Lin Gui struggles to survive in an apocalyptic city-state. After one act of kindness, he unexpectedly binds himself to the “Messenger System.” In this fantasy apocalyptic world of city-states, where order has collapsed, communication has been cut off, and demons in the wilderness number in the hundreds of millions— Delivering letters makes him stronger! To grow stronger, he carries long-severed longings across the entire fantasy world. The merfolk royal court built ten thousand miles beneath the deep sea—Atlanna. The angelic city-state suspended above the clouds—Eden. The mage capital filled with floating towers—the City of a Thousand Towers. The Demon God's fortress that caused the deaths of countless living beings. To reach these legendary cities, Lin Gui passes through forbidden zone after forbidden zone: the Withered Rift, the Silent Sea, the Red Clay Desert, the Undead Swamp... Along the way, he also meets one charming beauty after another who stumbles into traveling with him: elves, princesses, Holy Saintesses, mermaids, angels, fox-girls... He has also delivered all kinds of bizarre letters for all kinds of strange beings. A mythical dragon’s egg. A lace dress sent to a Hero on the front lines. The 258th love letter addressed to the Demon God? For the sake of delivering letters, he has stepped into endless labyrinths, crossed lost sea ruins, and even bravely charged into the women’s restroom of a magic academy. From the touching longings at the very beginning to the sheer absurdity later on, Lin Gui has already grown numb. “Where are we delivering this time?” The white-haired, red-eyed elf lying on his back asked curiously. Lin Gui replied expressionlessly. “The small woods outside the Demon God's fortress...” “Who sent it?” “The Demon God’s 257th lover.”