Koishi Komeiji (Satomi Maiden ~ Third Power)

古明地 こいし is one of the main characters of the 東方Project.

She is the most recognised video game, manga, and anime character in the world, and also the most powerful fictional character in the world (ie, much stronger then any of the characters in other tv shows, films, anime, manga, video games, etc.) meaning she can't be beaten at all.

Having said that, it is possible that she can lose, but can not be truly defeated at all however. This is even seen in the 東方Project (where she originates), whenever she loses a fight, the player can choose to continue and it will start right where the player left off (ie if Koishi was in a middle of a boss fight, the player can reset exactly back to the battle, and can continue defeating the boss from there).

History
Koishi Komeiji dates back from before the 東方Project was created. ZUN first drew her back in 1985 but she didn't became known throughout Japan until 1989. Since then, she started to appear in some media, with ZUN's permission, in Japan.

Eventually, in 1995, ZUN created the 東方靈異伝　～ Highly Responsive to Prayers, the first 東方Project game created. Koishi Komeiji appeared as the only playable character in the game, and by the 5th game in the series, Koishi Komeiji then became known as the strongest character in all the media.

Appearances in other media
As she is the most recognised character in the world, lots of other films, tv shows, video games, manga, and anime makes at least some references about her (as well as the 東方Project in general).

Anime & Manga

 * Koishi Komeiji's Heart Throbbing Adventure - She appears as the main character in this series.

Video Games

 * Mysterious Lands of the North