Rider's Master (Fate/Prototype)

Rider's Master (Fate/Prototype)
Rider's Master is 10-year-old boy, a victim of a "chimerization" experiment by the unknown antagonist of the last War, and has been hospitalized ever since. He had his Command Spell located on the palm of his left hand. He is the Third Master of the Holy Grail War. On the seventh day he used all his Command Spells, and made Rider fully incarnate, feeling that as Rider was someone who found happiness in life, his wish, the wish of a content man, will be a happy prayer to warm the heart of many.