Her psychic powers mutate the smallpox virus into a new strain of virus, called the "ring virus", one that causes anyone who contracts it to die, seemingly of fright, within a week. By Ring, in 1991, the Izu sanatorium, including the well that Sadako was thrown into, has been rebuilt into a mountain resort.

Sadako found out that she had leukemia. At that time they called leukemia the A-bomb disease . There was a low survival rate for 'A-bomb disease and Sadako was very scared. During Sadako's stay in the hospital, her best friend, Chizuko, came to visit her.