Mama wa Kyuuketsuki

Iyo is the daughter of the Seiki conglomerate's CEO. One day, her father returns from overseas and brings home a new wife. Her stepmother’s name is Ayako, and she moves into the mansion along with Iyo’s elderly biological mother. Ayako is exceptionally beautiful and is highly regarded by the mansion’s staff. However, Iyo simply cannot bring herself to accept her new mother. Furthermore, after her father leaves on a business trip overseas, strange events begin to occur around Iyo.

(Source: Kaiki Manga no Anagura, translated)