Katasumi and 4444444444 are two 1998 short Japanese horror films both directed by Takashi Shimizu, forerunners to the Ju-On franchise.

Kayako Saeki is the main antagonist of the Ju-On and The Grudge horror franchises. Kayako's fictional history alternates slightly between continuities, but all depict her as the very attractive yet unfortunately vengeful ghost of a woman killed by her husband, Takeo, along with their son Toshio, in a murder–suicide that happened after he came to believe she was having an affair. After the crime, the spirits of all three are bound to their family home, haunting and killing all who enter in the following years.