During the four years of development, Paradiso Phantasma met multiple changes, most of them influences by author's living experiences. The rest happened upon finding new inspirations such as the book Lesbian Love Addiction: Understanding the Urge to Merge and How to Heal When Things go Wrong, which led the story to retain the romance intended from the initial concepts while staying outside the tropes it goes against.
Here is the first piece of concept art, Luna's lips being spread by an unknown supernatural creature saying ''I bet you would look cute as a vampire'' with teasing intentions.
In Paradiso Phantasma's earlier days a Spanish translation was kept in mind. Luna's name would change to Lucía since the Earth's satellite is mentioned multiple times, confusion and redundance would ensue.
Cassiopeia is the reason behind the name Ghost Girl Phantasma. Meant to be a ghost, her entire narrative switched.
In the current version her nature is vague, open for interpretation and supporting both theories.
This drawing represents one of the concepts behind her death, missing an arm. The idea of her dying from a stray bullet meant to hit her lover was considered before scrapping everything.