Patchouli Knowledge is a character from the Touhou Project games.
Librarian and tutor for the Scarlet Devil Mansion household, and stage 4 boss. Patchouli is known as the "One-Week Wizard" due to her mastery of the seven elements of the Japanese calendar week. She is indeed a powerful elementalist, but suffers from poor health, which limits her battle prowess.
In the XP4 fics, Patchouli is a member of the Unlikely Heroes and ally to the Heroes Coalitions.
Shown in various works, her hair and eyes are purple, and has many ribbons tied to her hair and other parts of her clothing. She wears pink pajama-like clothing and a night-cap with a gold crescent moon on it, which ZUN says is her daily wear. Apparently, her dress looks like it has stripes of purple and violet. But according to ZUN, it's in fact not a stripe. This was confirmed in a talk of him and Twilight Frontier. In this talk, it says that even though they had acknowledged it by a material handed by ZUN, she ended up having a striped pattern in Immaterial and Missing Power for some reason. A conversation quoted from the talk: ZUN "Patchouli doesn't have any stripes." Twilight Frontier staff "Everybody thinks Patchouli has stripes except ZUN-san".
Her alternative outfit in Immaterial and Missing Power and Scarlet Weather Rhapsody is mostly lavender while her hair is a darker shade of violet.
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.
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") instead of Wu Xing ("wood fire earth metal water"). 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.
Elemental magic (also spiritual magic) borrows the powers of spirits that exist in nature. Through this, she's able to receive great output from a small input. Since the Wu Xing elements interact with each other, she can combine them and multiply their power, but this runs the risk of weakening the overall effect unless the elements are precisely controlled. When she confronts enemies that likewise use spiritual magic, then the interactions of Wu Xing would imply that she can somehow effectively use her own magic and somehow inhibit the opponent's magic.
Since the Wu Xing elements could be said to exist in living things, she touched upon them for characters who showed up in Immaterial and Missing Power. For example, Marisa Kirisame is associated with the element "water" according to Patchouli. Given Marisa's last name (Kirisame, meaning "drizzle"), her black clothing, her lack of yang (due to living in the Forest of Magic), and her "Cold Inferno" shot in Mountain of Faith, this makes sense.
She uses spell cards that combine multiple elements. In addition to using combinations with good compatibility such as Earth & Metal Sign "Emerald Megalith", she also uses combinations with poor compatibility such as Water & Fire Sign "Phlogistic Rain". Sun and moon are not within Wu Xing, but they're classically opposite to each other, and these two have been combined with each other in Sun & Moon Sign "Royal Diamond Ring". In Shoot the Bullet, she devised new experimental magic that combined elements with poor compatibility. With a large diversity of element combinations, she can do many things, such as increasing her power or covering her weaknesses. As of now, among the Wu Xing, the only combination that hasn't appeared is wood & earth.
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.
Fitting her magic to the same attributes as the days of the week is her secret hobby, but nobody has realized this. Thanks to this, she doesn't mistake the day of the week, but oddly enough she doesn't have a good sense of the date.
In Embodiment of Scarlet Devil, she had the peculiarity of using different spell cards depending on the player's character and shot type (a recurring gimmick in many stage 4 bosses of the Touhou games). Other than spell cards, she's able to use a revolving laser that focuses on herself as her regular danmaku.
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.
- Patchouli often refers to the science and technology of the outside world as magic. This is actually not ignorance, but more due to her personal beliefs, as she tells Marisa Kirisame in her Touhou Hisoutensoku victory quote that science and magic are the same.
- In Immaterial and Missing Power, Patchouli refers to intruders/thieves (e.g., Marisa Kirisame) as "rats" and guards (e.g., Sakuya Izayoi and Hong Meiling) as "cats". She rates the catness/effectiveness of a guard on a scale of 1 to 96, because that's the highest number under 100 that is divisible by both 2 and 3. After defeating Sakuya in Immaterial and Missing Power, she gave her a rating of 24. As for Hong Meiling, Patchouli compares that cat to a sieve in her Immaterial and Missing Power victory quote.
- The crescent on Patchouli's hat could be the crescent in the Sanskrit "Hum", part of the Mantra "Om mani padme hum". In Buddhism, it stands for knowledge and purity and is associated with the color white—all the 7 colors combined.
- As of Double Spoiler, Patchouli has had appearances in 9 of the 13 Windows games (counting Touhou Hisoutensoku as a standalone). This makes her the third most featured character, behind Reimu Hakurei and Marisa.
- In Touhou Hisoutensoku, one of Patchouli's alternate colors resembles Hina Kagiyama's outfit.
- The books in Patchouli's spell card, Fire Water Wood Metal Earth Sign "Philosopher's Stone", are arranged in a similar way to the Five Magic Stones.
- It's suggested in Immaterial and Missing Power that Patchouli drinks coffee occasionally when she's studying, unlike the other resident of Scarlet Devil Mansion who almost always drink tea.
- In Patchouli's theme Locked Girl ~ The Girl's Secret Room when the melody is made into morse code "・－・・ －－－ ・・・－ ・" it spells "love". There's also a song by ShibayanRecords called "・－・・ －－－ ・・・－ ・" that's a cover of the very song.
- Unofficially, Patchouli Knowledge's library was often called "Voile" based on its stage theme. However, due to an official list of errata published for Eastern and Little Nature Deity correcting the name of Patchouli's library from "Voile, the Magic Library" to "a library inside the Scarlet Devil Mansion", the name "Voile" is not considered canon.