Series: True Happiness Translated (kiriraitaa)

A happy yukkuri family takes it easy in a cavern showcasing their children, then a human comes along and it gets as well as it sounds. Later on, it gets revealed that the family was living in a concentration camp for Yukkuris, specifically for abyuse.

Arguably the greatest and most well known abuse story in the history of yukkuri fandom and pretty much why the fandom got infamous by the rest of the Touhou fandom

Untranslated/Light translated version: http://yukkuri.shii.org/pool/show/251