AboutABOUT: "Patchouli Knowledge" (パチュリー・ノーレッジ Pachuri Norejji)
Patchouli Knowledge is a witch and resident of the Scarlet Devil Mansion in the library. She's friends with the mistress of the house, Remilia Scarlet, and acts as resident librarian. She's known as a highly capable, experienced, and studious magician, usually found researching the countless tomes within the house library. But her great abilities are offset by her poor health, caused by long-time reclusivity and asthma.
She is a magician (or witch) who is over 100 years old. As described, she is the type of magician that was naturally born as a magician; rather than a human that has become a magician through training, such as Alice Margatroid.
She stays confined to the library of the Scarlet Devil Mansion because the books and her hair are damaged by sunlight. Despite her enormous magic power, she has a weak constitution, has asthma, is anaemic and has vitamin A deficiency. Her physical ability is worse than that of humans.
She doesn't have a very proactive personality, but rather always walks her own path. However, she's always interested where knowledge is concerned and will proactively go and try to acquire it. She does everything by the book, but still makes a lot of mistakes. She's also described as very dark and taciturn, which in this case means she is introverted and silent in expression and manner.
Ability: Manipulation of fire, water, wood, metal, earth, sun, and moon
Patchouli using the "five elements" makes her an "Eastern style Western magician", an antithesis existence to Marisa Kirisame: "Western style Eastern magician". Patchouli is able to handle the five phases (commonly called Wu Xing, sometimes known as the five elements) with the addition of the sun and moon elements. The order of elements she uses follows the days of the week on a Japanese calendar. Due to this, she's known as the "one-week girl".
In the Japanese language, the weekdays were named after the classical planets, which in turn were named after the Wu Xing phases (e.g. Mercury, water star), plus the Sun and Moon as heavenly bodies. As the ordering is based off of the planetary hours, there's no direct relationship between the weekdays and Wu Xing. The ordering of Patchouli's elements is unique in two ways. First, they follow the Japanese weekday ordering ("fire water wood metal earth" wink instead of Wu Xing ("wood fire earth metal water" wink . Second, her set begins with Tuesday (fire) instead of Sunday or Monday. It begins with the Wu Xing phases rather than the conventional days chosen to start a week.
While she's capable of using advanced magic with great power, her poor health, asthma, and anemia limits her ability to use it. During Embodiment of Scarlet Devil, she says "I can't finish reciting the spells because of my anemia!" and her condition limited her to using two-element spells. On another day, her asthma wasn't as bad and she felt better, so she was able to cast three advanced spells in a row: a sun, a moon, and a five-element spell.
Patchouli has many books that are in the library of the Scarlet Devil Mansion that's mostly used for magic. Some of these books appear to ack "independently" that can shoot danmaku, as shown in Stage 4 and Extra of Embodiment of Scarlet Devil. She also has waterproof books that Marisa finds interest in reading in the bath.