floating blue snake like ghosts

Some female ghosts seduce and kill trespassers on their mountain.

Spirit Of The Snake

A family are haunted by a Hebi Onna, a fabled demonic undead Snake Woman.

The Green Snake, who feeds only on demons and never harms humans, is misunderstood by the people of Hangzhou. Driven out and attacked, she escapes wounded and encounters a little ghost. The two decide to travel together. Upon entering the demon realm, the Green Snake attempts to rescue captured demons but faces skepticism and rejection. The Demon King, recognizing her abilities, assigns her a critical mission. As she spends time with the little ghost, the Green Snake begins to experience human emotions, and a deep bond forms between them.

The story of a woman cursed to occasionally transform into a killer snake. Followed by a 1990 sequel.

Killer snake horror.

Last part of the Snake Woman trilogy.