Sirenford Academy has a brutal hierarchy; students from aristocratic and influential families chastise and oppress fellow students from the common people. But one day, a group of masked rebels appears. Their name is “Penumbra” and they soon begin their hunt on the tyrants.

In a society controlled by the advanced artificial intelligence 'Giftear', everybody lives a seemingly perfect, fulfilling life. In this world, the young investigator Vivianne has to help a mysterious woman regaining her lost memories; But with every new discovery, the utopia's facade starts to c...