The characters are the mother, son (Kazuya) and this old dude, who somehow becomes the “master” of Kazuya’s mother and she is forced into having video-taped sex but most of the time she wears a blindfold to avoid her identity being found. The son has no idea about his mother’s activites but finds a pornsite where pictures of his mother with a blindfold on in all her glory. Kazuya has no idea that those pictures are of his mother and during the series he gets closer to the truth.
It also has a tragic ending ;)