Mukui wa Mukui, Batsu wa Batsu

Overview

After a bitter divorce from a cheating husband in America, Matsubaki returns to Japan and goes straight from the airport to the remote, mountain estate of her sister’s husband, Michiyuki. Her sister is missing, and she hopes to find some clue as to her whereabouts, as well as connect with her niece Kazuno. There are ominous signs right from the very start; she has trouble finding her way around the walled estate to some kind of entrance and ends up going in the back way through the expansive garden where she runs into Takiri, Michiyuki’s adult son from his first marriage. He brings her inside where she meets his older sister, the family’s would-be matriarch Sagiri, whose sole concern in life is her young son, Nami. Naturally, everyone is creepy in a strange way, the house is enormous, there is a well-meaning butler who helps Matsusbaki but in the most ineffectual way until he is murdered, and a family history shrouded in mystery. Oh, and creepy murderous children spurred on by a ghost. (Source: Brain Vs. Book)

Source: AniList