Because Sadako's mother has superpowers, and Sadako also has superpowers.

Later, Zhen Zi became two, one like her father was the later big Zhen Zi, and the other like her mother was the little Zhen Zi.

Because Xiaozhen is very bad (once killed a reporter who scolded her mother with her super power), her father (a doctor) injected her with growth inhibitors and kept her at home, so she never grew up.

Da Zhenzi goes to school like a normal child. The little Sadako is jealous that the soul of the big Sadako often attaches to her (it can also be said that Sadako actually has only one personality but two completely opposite personalities).

Big vibrator worked as an actor in a drama troupe after graduating from university. The sound engineer in the troupe likes her and she likes her, too.

Later Xiaozhen killed the original heroine, and then the director asked Dazhen to play the heroine.

But many people in the troupe reject Da Zhenzi (because it is often strange that Da Zhenzi is possessed by Xiao Zhenzi).

As a result, someone suddenly died on the stage during the performance (also killed by Xiaozhen). Everyone thought that the big vibrator killed her and called her a monster. Then a group of people killed the big vibrator (not actually dead but almost dead).

After Dazhen died, people suddenly realized that Xiaozhen did it, and then a group of people drove to the doctor's house with Dazhen's body to kill Xiaozhen.

Because Dazhen also has the ability to repair her body, she miraculously woke up again, but at this time she was badly hurt and exhausted. Xiaozhen took advantage of this opportunity to occupy her body, and Xiaozhen herself fell into the sea. Then Xiaozhen killed all the people who came to kill her and Yuanshan with Dazhen's body.

Then Zhen Zi's father knew that Da Zhen Zi had been completely possessed by Xiao Zhen Zi, and he was afraid that she would continue to kill people, so he injected her with smallpox virus, chopped her up and sealed her up in the well.

This is the whole story of the fourth film.

Actually, you can just look at it yourself. It's clear in the movie and the plot is not complicated.

Besides, The Ring of Midnight 4 is not scary, so it is a romantic movie.

You can read the plot by yourself. Why do you listen to others?