Based on the erotic doujin game by Circle Kurasuke Souko (さーくるくらすけ倉庫).

The creature that feasts on human memories and spirit, dream demons. The protagonist Night uses her power to battle these demons, and free people from their nightmares.

However, the one controlling the dream demons appears, and takes all of Night's friends, and everyone in her village away to her domain.

In order to bring everyone back, Night must battle those that control the dream demons, the "Wardens of Paradise"

(Source: DLsite English)