This is Larch, one of four characters available in Diabolica. More info on her will appear with the characters page. (side note: all characters are named after trees; alder, hazel, cypress, larch)
This also demonstrates the rotational turning that has been implemented. When turning to an opposite direction, character sprites no longer immediately face that direction. Instead, as they face that direction, they face a direction on the opposite axis of what they're turning on. (pardon my gif animation abilities, i had to manually simulate the effect)
For example, when Larch is facing up and turns down, she will turn to the right for an observable instant before finally facing down. When she is facing left and turns to the right, she will face down for an observable instant before finally facing right.
This does not happen when facing a direction on another "axis", aka turning from left to up, or from down to left, due to there being only 4 directions.