Luviagelita Edelfelt

Daughter of the Edelfelt family, a distinguished lineage in the world of magi.
She is considered to be one of the most promising students currently studying at the Clock Tower.
With her refined manners, elegant speech, and swan-like beauty, she was the very model of a perfect young lady.
That is, until Tohsaka Rin appeared before her.
It’s said that like attracts like, but which one attracted the other is a total mystery. All that can be said for certain is that the two of them were far too similar.
And so, the perfect young lady Luvia (who had been successfully hiding her true nature up until then) met her rival. From that point on, every time they saw each other they inevitably ended up quarreling.
By the end of the year, there was an unspoken agreement within the mineralogy department to not even bother going to classes that the two of them were scheduled to attend at the same time.
Luvia specializes in jewel magecraft just like Rin, and is a master-level user of Gandr. Of course, that second one is only natural, given that she’s from Finland.
She is a true perfect superhuman, and behind her graceful exterior is a neat freak that hates losing. Honestly, it would be strange if she didn’t clash with Rin. After all, there’s no need for two suns in the same sky.
However, although she might be a bit cranky at having the disguise she wore for so long suddenly ripped away, she seems to be having fun passing the days away with Rin, so it’s probably alright.
Also, though she’s just a student herself, she found the dorms too cramped for her liking and bought a mansion to live in instead.

Fate/side material: Fate Encyclopedia