koishi_komeiji's_heart-throbbing_adventure
Sentaku-bune's Niconico series, Koishi Komeiji's Heart-Throbbing Adventure (KKHTA).
Komeiji Koishi, an extra stage boss of Subterranean Animism, goes to upper Gensokyo to catch a fish for dinner, but she forgets to bring a fishing rod. Seeing the Scarlet Devil Mansion nearby, she decides to borrow one from them, and from there on Komeiji Koishi's Heart-Throbbing Adventure really begins...
Not all creepy Koishi pictures count. Look for things such as sharp claws, stitching on her 3rd eye, or the phrase, "My hat is my friend, it helps me relax."