Inside the Explanation Box about her, Misaya is described as "a perfect beauty". She is a young girl with red eyes and long black hair tied into a half up. She wears a white top with a black fur jacket along with navy short shorts and brown boots. She also wears a school uniform in a style like Ayaka's, as well as a V-shape red dress that reveals her Command Seals, located on the back of her neck.
She is a noblewoman; sadistic, proud, elegant, cruel, and calculative. Though not much is shown, a line said by her during the montage in Fate/Prototype was "I wanted to summon a Hero who was killed by a woman. That way he would know how scary a woman can be."
Despite what can be inferred by this, the Fate/Prototype Material book has a line from Lancer saying he likes her, as she reminds him of his teacher, Scáthach.
Fate/Prototype: Fragments of Blue and SilverEdit
Misaya is the version of Rin Tohsaka that was to be used in the original Fate/stay night novel which had been penned but was left uncompleted. In Prototype, information on her has been expanded on to show she has savage black dogs as her familiars along with her summoned Servant, Lancer. They worked together in tandem in order to hunt down another potential Master, Ayaka Sajyou, and kill her.
Much like Rin, she had lost her father in the War. However, she is cursed. The curse was cast by her father who had thrown everything away to attain the Grail, stating "Die if you do not become a Master and get the Grail". Towards the middle of the actual war, she would die due to this curse and her Servant, Lancer, would form a contract with Ayaka, who at that time had lost Saber to Berserker's Master, Sancraid Phahn.
However, it's said that the person who had really cursed her was not her father, but ■ ■. Her father had struggled to undo the curse, to no success, after which ■ ■ kills him. The curse covers her entire body, killing her. ■ ■ then transforms her into a "Fallen" (a shambling zombie).
Despite nothing being shown by the animated version beyond her created familiars and the capacity of sealing Gae Bolg, it's said in the Fate/Prototype Material that Misaya has the abilities of rune magecraft, black magic and all sorts of summoning spells.