Patchouli Knowledge is Remilia's friend and the most intelligent resident of the Scarlet Devil Mansion. She is a natural-born magician who has lived for over a hundred years. She spent most of those years reading and is constantly developing new magic.

Patchouli is capable of manipulating all elements except star, making her a very typical magician who specializes in elemental magic. Elemental magic borrows the power of fairies and spirits and, even with limited power, can be extremely effective.

Patchouli specializes in the magic of these seven elements: changing and moving fire, quiet and purifying water, living and waking wood, fruitful and abundant metal, foundational and unmoving earth, active and offensive sun, and passive and defensive moon.

Magic books are items imbued with magic. Whenever Patchouli creates new magic, she writes it down in a magic book. She then adds the book to the ever-expanding great library in the Scarlet Devil Mansion's basement. In addition to such instructional books for magicians, some say there are books in the great library that contain the secrets of how to become a magician...

Patchouli has a Spell Card called Fire/Water/Wood/Metal/Earth Sign: Philosopher's Stone. It takes the five basic elements of magic, turns them into crystals, and then uses them to attack. The philosopher's stone is a product of alchemy, not magic, but Patchouli managed to create one easily. Perhaps this is what gave rise to her Last Word within this world affected by a Lost Word: The Last Philosopher's Stone.