name: Matou Shinjiage: about 16 years old
nationality: Japanese
profession: student
family: his Grandfather Zouken, his sister Sakura.
likes: bullying, enjoying his popularity, planning his own interests
dislikes: Shirou, honest people, fair methods
magic powers: Weak. The tradition of his family weakened as generations passed.
servant: Rider (although he's only his temporary master), Gilgamesh (borrowed by Kotomine)
personality: Shiji is probably the second most disgusting person in thsi story. He's an old friend of Shirou but he seems he greatly dislikes him, although he always takes advantages of his kindness. He's always trying to show to the others how good he is, especially to girls he's supposed to be interested in, although he only seems to have a crush on Rin. He probably has a personality disorder that become worst when Rin refuses to go on a date with him. He's truly hurt by her behaviour and he can't forgive her for it. he's even ready to wipe out this insult with blood. Shinji doesn't either have a good opinion of her sister too, since she seems to be more interested in Shirou than in him (he abuses her, that's pretty sad) and that's an otehr point that increases his natural hate for the person he considers his rival. He's the vice-captain of the Archery club and it seems he enjoys it only because it gives him even more popularity. Shinki probably isn't that bad, in my opinions he's acting in that childish and mean why only because he really feels inferior to Shirou and he can't stand to loose to him.
spoilers warning !!!
personal story: Shinji is the eldest son of a family of anciet magicians, whom magical tradition weakened as generation passed. He doesn't want to admit his weakness at all and that's why he summons Raider, by borrowing her from Sakura and increasing her weakness due to this fact, and enters the Holy Grail War.
At the beginning of the first Scenario he desperatly tries to gather more energy making a sort of magical barrier at his school, absorbing the mana of the students and causing several accidents. Shirou and Rin eventually found out his plans and try to defeat him. Shinji tries to take advantage of his old friend with a false admission of his responsabilities, but just to backstab him. Rider is eventually defeated by saber and he's out of the War, although he ends up in being killed by Ilya at almost the end of the scenario.
In the second scenario he's useless as usual, and he demostrates, once again, to be a bad master for Rider. He loses her pretty soon and he asks for the help of Kotomine, who borrows him Gilgamesh, in order to go on in the conflict and get teh Holy Grail. But he's defeated again although eh manages to survive, at least this time.
In Heavens Feel Shinji is just a secondary character as Sakura finally gets the full control of Rider. He ends up in being killed by his sister and he turns to be the mechanism that made her fool.