Hello, is this a letter addressed to Demon Fortress?

Fantasy post-apocalyptic, walled city-state, road trip, ensemble cast
Nineteen years after transmigrating to another world, Lin Gui struggles to survive in a post-apocalyptic city-state.
An act of kindness unexpectedly led to his being linked to the "Messenger System".
In a fantastical post-apocalyptic city-state where order has collapsed, communication has been cut off, and hundreds of millions of demons roam the wilderness.
You can become stronger by delivering messages!
In order to become stronger, he traveled throughout the entire fantasy world, carrying the longing he had been separated from for so long.
Atlana, the royal court of the mermaids, built deep in the ocean.
Eden, the angelic city-state high above the clouds.
The City of a Thousand Towers, a city of magicians with towering floating towers
The demon fortress that caused the deaths of billions of lives.
To reach these legendary cities, Lin Gui traversed forbidden lands.
Withered Rift Valley, Silent Sea, Red Desert, Undead Swamp...
He also encountered many charming but fallen beauties who accompanied him.
Elves, princesses, saints, mermaids, angels, fox spirits...
They also delivered letters to all sorts of monsters and demons.
The eggs of a mythical dragon.
A lace dress sent to the brave warriors on the front lines.
The 258th love letter sent to the Demon God?
In order to deliver the message, he ventured into the endless labyrinth, traversed the lost sea ruins, and even braved the girls' restroom at the magic academy.
From the initial touching longing to the later abstraction, Lin Gui has become numb.
"Where are you sending it this time?"
The white-haired, red-eyed elf crouched behind him and asked curiously.
Lin Gui replied expressionlessly.
"The grove outside the Demon God's City-State..."
"Who sent it?"
"The Demon God's 257th Lover".