This is the fourth entry in the Flower and Snake series although as with the others the only thing in common is the title. The characters and story are different.
A dentist and his assistant chloroform, put in bondage and then sexually assault patients they find attractive. Then he meets a student of one of his patients he becomes infatuated with and adds some torture to the mix as he intends to make her a permanent slave.
There have been a number of Pink Eiga films that use a dentist as the main character, especially the Daydream movies from 1964 & 1981. This is a different take.
The cast is excellent especially Ran Masaki and Minako Ogawa who is outstanding and appeared in the previous Flower and Snake movie. There are of course the prerequisite sex scenes and nudity but nothing too explicit. The last scene being very erotic. Everything is softcore of course. The focus is more on the bondage and fetishes although in this entry they are woven into the story and characters. A couple of continuity errors but nothing major.
While not as strong as the first movie, this is still very good. Definitely a cut above the second & third. It stands on its own. You needn't have watched the previous Flower and Snake films.