This is Teletha "Tessa" Testarossa Summer Uniform White by Atelier Sai. And this is one of few figures I cannot recommend to anyone, especially with its weirdly high price tag. If you are asked to pay more than 70 USD on this, walk away. Even at 50USD, this is a maybe purchase. So, unless you are being given an absolute bargain, forget it.
I also advise you to stay away from figures by Atelier Sai in addition although this warning may not be justified based on just one figure.
The figure quality is below mediocre. The camera is not picking up the faults in a way that I am seeing it due to light level, but there are faults everywhere. Huge seam on her leg, most of paint lines are off, paints are inconsistent. The figure's large, 1/6, scale doesn't help and only magnifies the faults.
What a letdown, this figure is.
Perhaps the only saving grace is that her skirt is cast-off. Ironically, taking her skirt off reveals poorly-done underwear underneath.
But I will say this. The figure looks fine and gorgeous in the photos. Trust me though, the figure looks awful in real world.