Shin Megami Tensei Apocrypha: War of the Dove

A standalone story set in the larger Megami Tensei universe. Our hero Hato is just an ordinary schoolboy, until one day he receives a Command Spell Stigma on his left hand, forges a contract with Lancer Cu Chulainn to become his master, and is unwittingly dragged into a city-wide Holy Grail War.