Fate/Stealth Lancer

A 14-year-old named | ??? | struggles with anger management, often provoking fights, both verbal and physical. He has a strange habit of disappearing until he's ready to confront someone. Recently, he appeared in Fuyuki City with a new set of abilities, but had no clue how he got there. He finds this to be the perfect opportunity to pick a fight with some of the strongest people in history; now, he has to make the next three years until the Grail War simple. Right?