Note: This is based off the Vocaloid song Phantom Thief U's Scenario: Mystery of the Missing Diamond. For this version I will be using is the Hetaloid version. The characters will be as such:

Italy/Feliciano Vargas: The Journalist

Japan/Kiku Honda: The Auctioneer

America/Alfred F. Jones: The Mechanic

Germany/Ludwig Beilschmidt: The Police

Romano/Lovino Vargas: The Mafia

England/Arthur Kirkland: The Magician

Russia/Ivan Braginsky: The Politician

Prussia/Gilbert Beilschmidt: The Doctor

Lichtenstein/Lilli Zwingli: The Waitress

Hungary/Elizabeta Hedervary: The Actress

OC/Self-Insert: The Phantom Thief U

With that I hope you all enjoy this.

Prologue: The Phantom Thief's Declaration

It was finally time, tonight one of the most famous and priceless jewels would be on the S.S. Fantastic. It was the perfect time to strike. I knew that no one else would try such a feat; stealing the "Diamond of Happiness" from a heavily guarded passenger ship with so many people there as witnesses. But I wasn't an ordinary thief; no I was the renowned Phantom Thief U. I chuckled to myself. The fools on the ship wouldn't know what hit them. Of course that wasn't any fun, so I'd written some letters and planned on leaving them around town. They read:

At the auction party on the extravagant passenger ship, the S.S. Fantastic I shall come to steal the "Diamond of Happiness." Tonight, I shall put on the ultimate show of phantom thievery. – From the Phantom Thief U

After making sure everything was in order I left my house. The letters were safely hidden in my coat. As I walked around the city I casually let some slip out of my grasp, and to the ground. When I looked up I found myself near the docks. Another letter slipped from my hands to the ground. The auctioneer might as well have fair warning. By noon I had only one left. I was heading back to my place when a young man walked past me carrying a bag of groceries. His hair was brown with a reddish tint with a curl that was off to the left. His honey colored eyes were focused on the path before him. With a smirk I let the last letter fall, and catch in the breeze. Out of the corner of my eye I saw him pause and pick up the letter.

'My work is done for now. Hope you're all ready for the ultimate show,' I thought with a laugh.