Koakuma is a devil that remains a mystery in Touhou Project series. Not many info is known about her and she doesn’t make much appearances in game.
What is known is that she’s seen around the library of Scarlet Devil Mansion during the events of Embodiment of Scarlet Devil. Apparently she lives in the mansion. Her exact role is difficult to tell, but she is believed to be an assistant in Patchouli’s library there, due to being the midboss of her stage.
Touhou Koumakyou ~ the Embodiment of Scarlet Devil is a vertical scrolling shooter and the sixth official pc game of the Touhou Project series.
It is the first to be released specifically for the Windows operating system and the first by Team Shanghai Alice. All games before Embodiment of Scarlet Devil were made for the PC-98 series of computers
Koakuma model kits requires 5 sheet of paper to build, it is made by a Japanese designer which I do not know his/her name. It comes with a Japanese .PDF instruction