Mr. Calamity Wrote a Hundred Love Letters

"When the first blue rose blooms on the White Bone Coast, the elf king's eldest son will vanish from the continent forever."

This was Mr. Calamity's first prophecy, and the hundredth year since it came true.

As a messenger, Nabi's only job was to deliver personalized letters of warning from the World Tree to beings facing misfortune. That was why all the inhabitants of the continent liked to call him "Mr. Calamity."

"A mysterious forest near a dwarf village will catch fire in a hurricane."

"The Giant Clan's Howling Valley will collapse on a snowy night."

"A potion that causes suppuration will contaminate the canals of Dark Town."

Many beings had escaped disaster thanks to Mr. Calamity's prophecies, but they never welcomed his arrival.

Fortunately, the only place Mr. Calamity visited regularly was the Abyss in the distant mountains at the continent's northernmost edge.

Abaddon, the great demon king in the Abyss, was a truly unlucky fellow. He would awaken during a hero's sword-bestowing ceremony, and a volcano would erupt in the snowy mountains where he kept his treasures...

Mr. Calamity was very fond of this unlucky demon king.

So, in the most melodious elvish in the world, he rewrote Abaddon's calamities into love letters meant for him alone.

"Secret rules that exist as unspoken truths in the world":

1. Mr. Calamity's prophecies always come true.

2. Prophecy is all Mr. Calamity can do.

3. Mr. Calamity can set foot anywhere.

4. Mr. Calamity's prophecies cannot cross the Abyssal barrier to be delivered to the demon king.

5. Mr. Calamity knows that the soul he loves does not belong to this continent. The demon king comes from a distant, unknown land in the East.

Finally, every one of Mr. Calamity's love letters would actually be read by the demon king.

After reading each letter, the demon king would bury his head in his treasure hoard, hiding the pink-tipped horns on his head.

Subtle yet forthright disaster-messenger bottom x perpetually bashful, unlucky demon-king top

[Note]

As the blurb says, the top transmigrates, while the bottom is a native. The story will include content related to the modern-world timeline at the beginning.

The top is twice the bottom's size. The bottom can sit on the top's shoulder and enjoy the view.

Theme: Every line of text can be a love poem.