Vanished Age 7

Mayu the teen girl hasn't opened her heart to anyone since ten years ago when some terrible case happened. Instead of going to high school, she goes to the church every day and looks for redemption. One day, she disappears in the woods, silently and suddenly. On the other side, Mana lives with her husband and her seven-year-old daughter in happiness. However, an unexpected occurrence happens and tears their happiness apart. Her little girl Sakura plays in the woods and goes missing. Mana loses her mind because of sadness. What is there inside the woods?