A magician who lives in the Forest of Magic, Marisa first appeared as the Stage 4 boss of Story of Eastern Wonderland and became a playable character in every game afterwards, eventually becoming the secondary protagonist of the Touhou series. In the Windows games Marisa is established as Reimu's best friend (and friendly rival), the two having known each other since they were kids. In contrast to Reimu, who was strong from the day she was born, Marisa is a completely normal human with no innate supernatural abilities... not that she let that slow her down. Nowadays she takes pride in her status as an "Ordinary Magician" who earned her spot in Gensokyo's list of notables through nothing but persistence and hard work.

Marisa is rude, loud-mouthed, and a notorious liar and thief, but also a very straightforward person. Despite her rough edges, between her and Reimu she's portrayed as the friendlier and more sociable main character, with enough connections in town and elsewhere to always know the latest gossip. She is also more sentimental than Reimu, and tends to worry more actively about the safety of the human village even if she doesn't admit it. Due to the amount of research and experimentation required for her spells, she can be surprisingly knowledgeable about science and magical substances (albeit as a resident of Gensokyo, her understanding of Outside World science tends to be distorted at best).