Patchouli Knowledge is a magician known as the brains of the Scarlet Devil Mansion, the manor where devils live.

It is her role to resolve problems that occur there (*1).

She has long hair, but otherwise her appearance is indistinguishable from a human's.

She is purely a magician, and it is said she has lived for over a hundred years.

Astonishingly, it is also said she has spent most of those hundred years reading books.

She is proficient in various types of magic and eagerly researches new spells.

Whenever she devises a new spell, she inscribes it into a magic book, expanding the library.

It's unknown when exactly she settled into the Scarlet Devil Mansion, but judging by the size of the library, it must have been a considerable time ago.

1: At the same time, it is her role to cause problems as well.

She is a magician's magician, able to cast various sorts of magic.

She mainly uses elemental magic.

Elemental magic borrows on the power of fairies and spirits to result in an output greatly exceeding the small input.

Elemental magic is comprised of seven varieties: "wood," for life and awakening; "fire," for change and movement; "earth," for foundation and immobility; "metal," for wealth and abundance; "water," for silence and purification; "sun," for activity and offense; "moon," for passivity and defense.

While being able to use magic from all these elements, the surprising part is that it seems she is able to cast spells that combine two or more elements.

Moreover, her variations are extraordinarily abundant. She can combine fire and wood to increase her power, or combine fire and earth to cover her weaknesses, and much more.

Grimoires, or magic books, are not simply books, but are magical items with magic power sealed inside.

Their contents are not simply directions on how to cast magic, but the secret keys to the use of magic itself.

In theory, anyone could cast a spell if they had the appropriate magic book, but without finding the key inside, it would not be possible to understand what is written within.

One cannot find the key if they do not possess equal or greater skill than the person who wrote the grimoire.

The letters written in the book are not the system used by humans, but are said to be divine-era hiragana, or perhaps the original Japanese writing system.

There is a great library beneath the Scarlet Devil Mansion filled with veritable mountains of magic books.

There are many magic books that she has written, as well as many that no one has been able to read.

The library holds a great many books besides magic books, as well.

Most of this material consists of books from the outside world (*2).

2: Gensokyo's books are primarily handwritten. There are few properly bound and published books.

"That library reeks of mold." (Marisa Kirisame)

Since Japan is quite humid, archives are typically built in well-ventilated areas.

Since the Scarlet Devil Mansion is a Western-style building, it may not have been made with Japanese climates in mind.

"There's the occasional book that is readable sometimes." (Reimu Hakurei)

One can read a book from the outside world just like any other book.

I would also like to try reading one.

The characteristic of elemental magic is to create great effects from a small amount of power, but there are flaws to this approach.

That is because each element has its own weak point.

This applies to her magic as well.

If by some chance you end up in a battle with her, you must stay alert to which element of magic she is using while fighting her.

But since she seldom leaves the Scarlet Devil Mansion, battles with her are extremely rare.

As long as you do not break into it, there will be no chance of fighting her.

In addition, her physical condition is poorer than that of a human's.

Since she is asthmatic (*3), she can't exert herself too much, lest it becomes difficult to breathe.

This places her in an unusual category among youkai.

3: As is characteristic for a magician, she can speak extremely quickly in a low voice. It's suffocating to watch her speak so quickly even with asthma.