I don't see why people are reacting to this doujin by saying "they're both creepy". Flan is an overpowered child with an infantile view of the world. Koishi's a raving serial killer who enjoys mentally torturing people until they commit suicide for the giggles. Those two aren't on the same level.

I'm not exactly a Flan fan, but stories like this and Heart-throbbing are exactly why Koishi is becoming one of my least favorite Touhous.

You realize canon Koishi is nothing like the Koishi in this or KKHTA? She'd never actually abandon spell card rules just to kill someone for shits and giggles.. This is all just fanon.