Marisa is a human witch who lives in a cluttered house in the Forest of Magic. She is friends with Reimu and visits her often, but otherwise is solitary and spends most of her time researching magic. She is also an avid collector stuffing her house with various items, and would go "borrowing" things from others without returning them.
She is selfish, sometimes violent, and has a disagreeable manner. Underneath, though, she is honest and a hard worker. This makes it strange that she is friends with Reimu, whose powers are purely from talent while she had to work very hard to get her own to the same level.
Her ability is high-level destructive magic.