Marisa is very straightforward and informal with everyone. She can be condescending, as if trying to make fool of others, and often has difficulty expressing sympathy. She's quick to act if she hears anything interesting. Marisa is also a habitual liar, but she makes no effort to actually deceive as her lies are extremely obvious. However, she's shown to have intelligence. Her personality appears to be somewhat charming due to the friends she has and her ability to walk into the Scarlet Devil Mansion so casually.
She has a mania for collecting things and may have a hoarding disorder. She's unyielding and unco-operative. As a hard worker, she's very diligent, but she doesn't like others to know that.
Unlike most characters, Marisa is known to use a distinct speech tone. The most typical and known example of this is the use of the sentence ending particle ze (ぜ). "Ze" used at the end of verb stems delivers a "mannish" and "impolite" sound to the listener/reader. Ze is mostly used in a context to express one's will to act (similar to "let's" in English), and using it in other cases sound somewhat unnatural, perhaps "phony" or "showy". While she does speak in a rather "manly" tone, she doesn't speak in a "rough" and "masculine" language, but in an "impolite/casual" and "boyish" one.
In the PC-98, Marisa's way of speaking included "~da ze" at the end of sentences and "~ka?" at the end of questions as well as using watashi (私, lit. "I") (frequently considered to be masculine). However, in Story of Eastern Wonderland, she used atai (あたい, lit. "I") and the expression "kyahaha", which are feminine. Other than the fourth stage in Phantasmagoria of Dim. Dream and Lotus Land Story, her use of "I" had become "私", but she laughed with "ufufu". Furthermore, in Mystic Square she didn't laugh, and, other than femininity, she had become pretty much the same as she is now. Also, although in Embodiment of Scarlet Devil and Perfect Cherry Blossom there are a few traces of PC-98 references, she didn't say "~desu wa" in the PC-98 canon as she does today.
In the endings of the later PC-98 games her speaking style was pretty much the same as she is now today, and in the earlier game Phantasmagoria of Dim.Dream, Chiyuri Kitashirakawa had a speaking style resembling Marisa in Windows canon. This could have been one source of influence. Although at first in Shuusou Gyoku, she spoke femininely, but immediately she then began to use a speaking style that's the same as she uses now.
- Mario: Intrested on him, as Marisa both has a slimar first name as Mario as well having a thing for mushrooms.
- Rosalina: Marisa doesn't really like Rosalina much.
- Jeff: Marisa constantly steals Jeff's things.
- Nico Yazawa: Marisa doesn't think much of Nico.
- Maki Nishikino: Maki's behavior reminds Marisa of Alice.
- Alice Margatroid: Marisa's Love intrest.