The first seven, China people's funeral custom, is based on the time of the deceased's death, plus the date and hour calculated by heavenly stems and earthly branches, but everyone used to think that "the first seven" refers to the seventh day after death. Different places have different "first seven" customs, but it is generally believed that the soul of the deceased will go home in the first seven days, and the family should prepare a meal for the soul of the deceased before it comes back, and then it must be avoided. The best way is to sleep. If you can't sleep, hide under the bed. If the soul of the deceased sees his family, it will make him miss and affect his reincarnation.
It is also said that the soul will wander around before the "first seven" after death. When they go home at noon on the first seven days, their families will burn a ladder-shaped thing at home and let their souls go up to heaven along this ladder.
Visit at home seven days before death. It's from the Hidden Death Sutra (also known as the Secret Method of Saving Yin).
That's why it's a horror movie.