TV-Series
Description
Nail Saionji is a frail young boy with dull blonde hair and pink eyes, often seen wearing white-rimmed ovular spectacles and simple clothing consisting of a white shirt, pants, and shoes. Alternatively, he is described as tall and slim with a pale complexion, shoulder-length pale blonde hair, brown eyes, and oval-shaped glasses, dressed in a light blue coral shirt, light steel blue skinny pants, and white Chelsea-like boots, with a golden ring on his right index finger.

He is a polite and analytical individual who deeply believes in the concept of "setsuri" or providence, often questioning established norms. His personality is introverted, cold, mysterious, calculating, and meticulous, marked by a strong dislike for cowardly behavior and cheating. He exhibits an eccentric fascination with providence and operates primarily out of curiosity.

A child prodigy, Nail hacked into Goha Corporation's system at the age of three, destroying a large portion of the satellite network and causing debris to rain down on the city, disturbing his parents. They introduced him to Duel Monsters to curb such behavior, and he quickly became infatuated with the game, demonstrating proficient skills and winning a tournament against an older duelist. He later became an employee of Goha Corporation, overseeing the entire dueling network and receiving a personal unit called the Garden of Providence, along with an A.I. named Sebastian. During his tenure, Otes approached him with a "relic," disrupting his control of the network and predicting the emergence of a new King of Duels. Initially ordered to eliminate Rush Duels, Nail became intrigued by Yuga Ohdo's creation and eventually implemented the Maximum Summon rule into the system.

Nail uses a Cyberse Deck that focuses on maintaining advantage through various "tron" monsters, including "Femtron," "Attron," "Yoctron," and "Zeptron," which replenish his hand, send cards back to the deck, or send them to the graveyard depending on the situation. His strategy involves using "Hole" Trap Cards to counter opponent's monsters and protect his combo, ultimately aiming to Maximum Summon "Yggdrago the Sky Emperor" (also known as "Yggdrago the Heavenly Emperor Dragon Tree") by assembling its "Left" and "Right" counterparts to unleash powerful effects and high attack power. His cards draw inspiration from the World Tree, Yggdrasil, from Norse mythology, with "Yggdrago" representing the tree itself and the "tron" monsters symbolizing its leaves.

His recorded duels include victories against an unknown duelist, the Tops of Hexagon, Yuga Ohdo, and Sebastian, a draw with Gakuto Sogetsu, and losses to Yuga Ohdo and Asana Mutsuba. In the video game "Yu-Gi-Oh! Duel Links," he appears as a Legendary Duelist with various skills and deck levels centered around his curiosity and Maximum Summoning strategy, including abilities like "Rush On - Yggdrago" and "Maximum Ragnarok."