Written by Koji Suzuki.
Following a divorce, Yoshimi Mitsuba and her 5-year-old daughter Ikuko have spent the last three months making a life for themselves in a small apartment. During a trip to the roof to light off some fireworks, they discover a Hello Kitty bag.
What follows is a creepy, unnerving story which definitely stands as one of Suzuki's better horror pieces. The bag makes a few return visits, her daughter starts talking to an invisible friend in the bathtub, elevators move on their own, shadows and presences abound... and it all leads to a little girl whose family moved out of the building several years prior following an unexpected tragedy.
While he piles a few too many scares in a sequence near the middle, and a vision at the end hammers things home a bit more than necessary, it's all quite well executed and Suzuki earns bonus points for building a rich, real life around Yoshimi which adds a nice worldliness to the material.
I feel an interesting point of debate arises with the ending. In the story, it all comes to a close with a revelation about the dead girl's tragic resting place. Suzuki handles it beautifully, setting up Yoshimi as an obsessive, phobic individual who eventually comes face to face with her worst, most repulsive fear.
The films, on the other hand, follow Ring traditions and keep the ghost around for a further twist which plays on some simple "mommy" issues. While nicely executed in the Japanese version, I don't feel any of it's really necessary. A woman who hates filth finds that she's unknowingly exposed both herself and her daughter to the worst kind. That's all the ending you need right there and it's a shame neither film made much use of it.