The curse of Yamamura Sadako
Original title: The curse of
Year: Unknown (Japan)
Storyline: At the age of 8, right after the dreaded Shizuko's ESP demonstration, Sadako splits in two parts...
Review: Well... this is the explanation, missing from Ring 0: Birthday (the movie) - it shows the key part of it: how Sadako split herself in her evil and good twins (who then re-join near the end of Ring 0: Birthday). This story does a very good job in showing how Sadako split in two, and believe me, the events in this story are what is missing from Ring 0: Birthday. I think that if Ring 0: Birthday was merged with this story, it could even reach Ring (1998)'s classic level. But however, both this story and Ring 0: Birthday are also very good by themselves, and you can always think of the Ring movies timeline, and add the events of this story into it. It simply needs to be there.