This one is about yukkuri factory that harvest yukkuri for resource. This one in particular is a research report about harvesting Astron metal.
They use a mother and child pair and put them in situation that forced the mother to change into Astron mode. Then they also found out the hardness increase as the mother tried more to protect her child, although it's still crushed in the end.
At the end of the story, little Reimu is compressed but still alive in a 2cm space created by last pieces of her mother. But the researchers never realize this as they already have their data and out for the day.