One year after the events of Mai-Otome, an asteroid on a collision course with Windbloom kingdom is destroyed - barely - by an international task force of Meister Otome. Subsequently a new and more powerful kind of Slave appears, along with a sinister black-robed entity - or entities - able to easily overpower the most powerful of Meisters. Not only this, but Arika and Mashiro's troubled relationship is hindering the use of the Sapphire of Azure Sky - possibly the one weapon powerful enough to defeat this new adversary.