Hebi Shoujo: Umezo Kazuo Kyoufu Gekijou (1965)

A trio of related short horror stories. In "Scared Of Mama", Yumiko is looking forward to her mother’s return home from a long stay in hospital but things don’t go as planned after another patient - a mysterious snake woman - takes her mother’s place. Yumiko will have to avoid being eaten long enough to reveal the imposter. In "The Spotted Girl", Yumiko travels to the countryside to visit her cousins. Little does she know that the snake woman, out for revenge, has stowed away in her luggage. In "Reptilia", we discover how the snake woman came to be and find that Yumiko is not the first girl to fall victim to the snake monster of Shinobazu swamp and her descendents.

Source: www.anisearch.com/manga/1909