The Spirit Parasite Demon was, just like its name, a demon that lives through parasitizing a host and using the host's energy as its sustenance, to gain strength.
The problem with this was that the parasite would return some of its gained strength to its host, maintaining a "fake" mutually beneficial relationship between them. This causes the host to lose the will to fight against the parasite, allowing it to gain even more strength in the process.
Furthermore, as long as its host is alive, the parasite will continue regenerating from any damage. Thus, a Spirit parasite was a tricky opponent to handle.
'The easiest way to kill the parasite is to kill the host. However, the challenge lies in our inability to eliminate the infested spirit.'
