For starters, there are many MANY characters, all of which are female.
Touhou is a Japanese game series created by ONE bloke.
Touhou has many fans that have created songs and extended back story to the characters. In one of the games when your trying to defeat the character Cirno, there is a spot in easy mode where you will never be hit by her attacks. This led to her being called a baka, or idiot, by the fans. Zun, the creator of the Touhou games, created a manual in the next game which had a picture of the characters on a screen shot of the game. Each character was headed under a specific number. Cirno was headed under number 9, but instead of naming her, she was named 'baka' instead! ROFLOL. Hense why she is a ⑨
This next song is about Suwako. The tune is a remix of her level from the game.
This is Cirno's reply-
For some reason there will never be an anime series. But this hasnt stopped the fans from trying-
And lastly, these videos should show you just how insane the fans are:
update with extra videos-