Kyoko builds a shrine for her mother after she suddenly passes away (implied to have been killed by Kayako draining her life force, similar to Sachie in the first film). She occasionally sees her spirit in her house after the fact. This is because in Japanese culture, constructing a shrine for your loved ones after they pass away would allow their spirits to watch over their family peacefully.
The first film in the Ju-on series that does not feature the ghost or presence of Takeo Saeki.
Kei Ohishi wrote the novelization for the previous film and returned to write the novelization for this sequel.
Would be the last installment in the Ju-on series to be written and directed by Takashi Shimizu.