Shirou is the main character of Fate/stay night. He is a serious yet helpful, hardworking, and honest teenager. His hobbies include fixing a variety of broken things, from VCRs to stoves, as well as cooking and cleaning. He has some slight talent with sorcery, though he was discouraged by his foster father Kiritsugu Emiya from improving his gifts. He is initially confused about the Holy Grail War and attempts to irrationally shield others from danger, including his own Servant, Saber.
Shirou is unskilled in most traditional forms of sorcery, and his only effective magic is Reinforcement, the power to analyze the structural composition of objects and increase their effectiveness by understanding their chemical and physical makeup, such as the sharpness and durability of a sword and shield. However, he lacks mastery for even this simple spell, and his various applications of it are limited.
While Shirou is struggling to learn Reinforcement, the first magic he learned is Projection, which is a much less effective magic compared to Reinforcement. However, Shirou’s projection (referred as Tracing) is fundamentally different from normal projection. While initially it proves to be an useless skill due to the fact that Shirou can only produce hollow objects, the projected item can remain in the world for a long time. Later on, due to Shirou’s Sword Affinity, he is able to copy the history and special properties of bladed items, even noble phantasms, though they are of slightly lesser quality (They are downgraded one rank from the original). At the culmination of his abilities is his Reality Marble, Unlimited Blade Works, which is the source of his unusual projection magic, Projection and Reinforcements are simply by-products of it. Unlike the normal projection which simply shapes an item out of prana, Shirou’s projection summons the item from inside Unlimited Blade Works without expanding the reality marble. When expanded, Unlimited Blade Works manifests itself as a barren wasteland covered in swords, but with a beautiful dawn in the sky. In there exist all of the materials Shirou needs to recreate any bladed weapon, and Shirou is able to control all of the swords in Unlimited Blade Works using only his mind, using them to attack his opponent without having to physically touch them.