Ao no Haha

Attempting to shake off a nightmare from her childhood, Itoko was supposed to be married in the village of Migomori. There, she saw a doll that looked just like herself. Itoko wonders why this doll was made and what is the "mother of blue" the villagers speak of. Itoko feels herself being dragged into an abominable village tradition and another nightmare. (Source: AniList)