Tetsu no Monsho

Translates to Iron Emblem. A pen-and-paper RPG (an RPG played on a tabletop with multiple players and one called a game master) made by Nasu in his student years (during middle school, Nasu spent his days creating his own world in which he played with his friends). Very little information is known about this work, as of 2008, TYPE-MOON had registered the trademark for 鉄の紋章.