From the first two panels, it looks like other yukkuri were transplanting their stalks to Sanae against her will and then being surprised when she didn't have the strength to bring them all to term. The stupidity and evil astounds me.
Sanae is treated as slave seedbed by the clan. The parents planted their stalk to Sanae so they can just play or hunt.
Sanae is taken since she's born and kept in darkness of the hole she's now living in. They feed her with rotten food and poop. Sanae want to just starve herself to death, but she don't want to kill the babies planted on her. Although one day she will die, she also know that by then, the clan would rape her and take her daughter to replace her.]
When baby Alice is born, she's so happy. She want to answer their call and move to the babies who's afraid of the dark, but her voice and legs are already damaged. She can only watch as the mother Alice called her babies from outside the hole.
Then when the babies die, Marisa beat Sanae and rape her.
After that, Marisa go back to her wife, and next day they already have another set of babies.