What アニメ is this girl from?

I've seen her seen her too, alot.....But I don't think she is from any Anime.....

she not fm a アニメ but nightcore

I'm pretty sure that's Rin Kagamine. She's not from an anime, she's a VOCALOID. It's a voice synthesizing softwear created によって Yamaha to make anime-like characters sing and perform.

No it's not Rin she looks like this :
Her hair is もっと見る yellow
And she almost always has that outfit