LSD is based on a dream journal authored by Hiroko Nishikawa, a staff member at OutSide Directors' Company. The dream journal was originally titled "Beautiful Dream Journey".
Both the journal and the game document vivid, odd dreams over the course of a single year, although there are very few direct similarities.
- Both the journal and the game take place in similar settings such as a "creepy, empty town" and a "circus with many connected tents".
- Some of the white text on the black screen is said to reference "Not having a dream that night", or dreams being "Too horrifying to recount". These are frequent entries in the journal.