It was made into a 1999 Japanese film, Himitsu, directed by Yōjirō Takita.

Monami makes a miraculous recovery—albeit, with one small twist—her personality and memories are that of her mother Naoko's, rather than her own.

Both Heisuke and Naoko conclude that her spirit is possessing Monami's body.

Unable to explain what has happened, they decide to keep the matter a secret while Naoko lives as Monami from then on.

As Monami's possessed body enters adolescence, Naoko takes the opportunity to live her own unfulfilled dreams.