A meteorite hit the Earth in the past leaving pieces of jewel - source of great power.
Nine years ago Enomoto-sensei who helped a mysterious organization study the jewels died leaving the secret of the jewels in the hands of his daughter Koriko.
This days Koriko returns from her study trip to America to find proper girl candidates to master the power of this dangerous source of power - risky jewels. Three young girls will need to use its power for transformation if they want to defend the world from the mysterious organization.

[From vndbreview]