The story is a brother, sister & the brother's fiancée travel to the home left to them after the father died. The father has a bottle collection with one particular called "The bottle of hopelessness." That bottle originally contained a note from another brother & sister (not related to the first set), marooned on an island that committed incest and seemed to entice the other brother & sister closer.
The story is actually very interesting. The bottle plays an important role throughout the movie. Well thought out script. The acting was alright but the actress that played the sister didn't look anything like the actor playing the brother. The actresses that played the girlfriend & sister on the island looked closer. Just something I kept thinking while watching.
As for the sex. This is a Nikkatsu Roman X film. Roman X was a line of films in the 1980's to compete with Adult Videos (Japanese porn) coming out, supposedly to contain unsimulated sex. Most of the sex here looked like probably simulated/fake. Or at the least you couldn't see anything as the Japanese censorship of the time was in effect. Some others films did contain real unsimulated sex like Daydream from 1981 and Woman In the Box: Virgin Sacrifice although mosaics & fogging prevented anything explicit being shown.
There are more than the normal number of sex scenes for a Pink Eiga but I didn't think they were all that exciting. So I wouldn't recommend this film to watch for the sex if that's important to you tho they are a part of the story itself.
Still I did enjoy the movie as a whole.
