Where's My Knife?

[Sickly boss of the criminal underworld top x gorgeous, battle-hardened divine weapon bottom]

This is a world where divine weapons reign supreme across the Six Realms.

Everyone in the Six Realms, whether mortal or god, demon, or monster, is born with a mayfly lantern. When the lantern lights up, it means a divine weapon has summoned them.

Everyone knows that the Demon Lord Feng Nanxiao has no divine weapon. Some say he was born with power that surpasses the Six Realms, and looks down on all beings, disdaining the use of a blade. Others say his mayfly lantern has never lit up.

Hearing that the Divine Realm had appointed a stunningly beautiful new God of War named Changji, the Demon Lord eagerly challenged him to a fight.

The young God of War was inexperienced, so he drank for courage before accepting the challenge. His features were already delicate, and even his threats came with rosy lips and pearly teeth. The Demon Lord was so smitten that he held back, merely raising a hand to snap the young god's weapon in two. He never expected the glasshearted God of War to be so devastated by the destruction of his divine weapon that he took his own life.

After the young God of War died, his obsession became a wisp of lingering soul and fell into the Divine Weapon Pool. Before long, an unparalleled divine weapon emerged.

But the destined person this weapon followed turned out to be an idle immortal from the Divine Realm. Pure-hearted as he was, the immortal would shed a few tears even over a broken celestial herb. So when he saw this demonic blade, he promptly abandoned it, tossing it down into the mortal world.

Feng Nanxiao brought the divine weapon home while injured and named him Changji. Day and night, he nourished him with his own blood, raising him with bowl after bowl of blood, with all the care and hardship of a parent.

A hundred years later, Changji was forged into a blade and took human form. But to everyone's surprise, he switched sides on the spot and went after his immortal lord without looking back.

The Demon Lord woke from a nap to find his precious blade missing, and his old illness immediately flared up.

The Demon Realm descended into chaos.

His left and right guardians were frantic, scouring the world for the blade.

Where's the Lord's blade?

Where is the Lord's blade?!

Who knows where the Lord's blade went!?

Report!

The Lord's blade ran off with someone!!!

[Slow-burn relationship: sweet, then angsty, then sweet again]

[Asthma trope]

Theme: Who will claim the world's finest divine weapon?