Kara no Kyoukai (空の境界) is a series of novels by Type-Moon's Nasu Kinoko. Kara no Kyoukai takes place in the same universe as Tsukihime and Fate/stay night, and features the main character named Ryougi Shiki who possesses similar powers to Toono Shiki.
It was published before Tsukihime, and is considered to be a prototypical version of the game's story.