Mitsuzuri Ayako

A female student in Class 2-A.
She is the captain of the archery club, and friends with both Emiya Shirou and Tohsaka Rin.
Well, Rin is her friend, while she treats Shirou more like a rival. The three of them haven't noticed what a delicate relationship they have with each other.
Her big-sisterly disposition exceeds even Rin's, and she's considered one of the top three students at Homurahara Academy to avoid picking a fight with.
People tend to think that she's mannish, but privately she's actually pretty girly.
Of course, this clashes with her image so she doesn't go around advertising it, but she doesn't really think it's a big deal herself.
Even though her room at home looks more like it belongs to a little girl than a teenager, she has no qualms about inviting Rin over to hang out. After all, it's not that she has no interest in romance, it's just that she has a thing for older men. Could it be? She and Rin are united by their father complex!?
Though it may seem odd that a supporting character has such spirited looks, it's only natural given that originally her design was conceived of for Rider.
During the preliminary stages of development, the scenario director was obsessed with a movie called “Vi(…)ck,” and kept on insisting that Rider should be more like a certain black-caped character.
Mitsuzuri's design was an attempt to meet his demands that unfortunately ended up being rejected. Still, it seemed like a waste to just throw out such good work, so it was ultimately resurrected and recycled into Mitsuzuri Ayako. Thank goodness, yeah?
Saying she resembles Ryougi Shiki is strictly prohibited.
By the way, after the Rin route she's still as energetic as ever. And in case you were wondering, yes, the person who attacked her was Rider. She chased her down into a back alley and SLUUURP, sucked her blood on the spot! I sure hope she didn't pick up any weird habits from that, nyahaha.

Fate/side material: Fate Encyclopedia