Sieg

Sieg is a slender young man with messy brown hair and deep, ruby-red eyes that reflect his artificial origin. He wears a professional ensemble consisting of a white dress shirt under a black waistcoat, paired with black trousers and sturdy boots. Though initially frail, he possesses a hardy build and often carries the ornate silver sword of the Rider of Black.

Selfless, brave, kind, logical, naive, and polite.

Master and Savior

Created as a disposable mana source by the Yggdmillennia family, Sieg escaped his tank to seek a life of his own. After being fatally wounded during his flight, he was saved by the hero Siegfried, who sacrificed his life to transplant his heart into the boy's chest. This act of heroism allowed Sieg to participate in the Great Holy Grail War, where he fought to protect his fellow homunculi and eventually transformed into the dragon Fafnir to safeguard the world.