This is the prequel of My-Otome, which predates the events before the My-Otome Series. In this series, it focuses upon the origins of Lena Sayers, the mother of Arika Yumemiya and former bearer of Lofty Crimson Jade / Blue Sky Sapphire GEM, and Sifr Fran, the biological mother of Nina Wáng and the former queen of Windbloom Kingdom, as well as the origins of Schwartz, Aswad, and the Garderobe Academy and its Five Columns. The kidnapping of Sifr and the powerful revelation of Lena's GEM will soon fatefully determine the outcome of the future for themselves and the others around them.

My-Otome Zwei takes place one year after the events of My-Otome. Arika is now a full-fledged Otome (though still under the tutelage of Miss Maria) and Nagi is incarcerated in a prison somewhere in Aries. The various nations are at peace with one another and plan to hold S.O.L.T. (Strategic Otome Limitation Talks) to discuss limiting the numbers of Otome. A mission to destroy a meteor threatening to collide with Earl sets into motion a chain of events which result in a mysterious shadowy figure attacking Garderobe and several Otome as well as a new, more powerful version of Slave appearing across the planet. To make matters worse, Queen Mashiro disappears following an argument with Arika. The series follows Arika's search for Mashiro as well as Garderobe's attempts to uncover the truth behind the shadowy figure.

Aika is a smart and athletic high school girl. She is so competent that she successfully passes the salvagers license test, obtaining a C-class license. Yet, she is young and hotheaded, so much so that Gota still treats her as a child. Due to this personality, no one is willing to hire her for salvaging jobs. Since she had taken the trouble to get her license, she decides to post an ad in her school to attract clients. She manages to get the attention of Erika, a daughter of a rich family and the leader of the treasure hunting club. She asks Aika to salvage something from the sea and Aika delightfully accepts the request. However, upon seeing the state-of-the-art submarine loaded onto Erika's private cruiser and discovering their destination, Aika realizes the terrible nature of her assignment. This results in a clash with a group of high school girls in the southern islands. Who is the mysterious girl named Karen? So begins Aika's newest challenge!

This is the story about how Dubus, Lafiel's father, and Plakia after an adventure on a mysterious, abandoned spaceship decided to have a daughter together and why Dubus gave her the name Lafiel.