|Mai-Otome Zwei episode|
Japanese DVD cover for Mai-Otome Zwei Volume 4
|Episode no.|| Season OVA|
|Original airdate||August 24, 2007|
|Mai-Otome Zwei episodes|
The episode opens with Irina Woods and Yohko briefing Natsuki on data sent back by Nao to Garderobe just before she was turned to stone. The data reveals the shadowy figure to be Yuna, a planetary annihilation weapon from the past that had been ejected into space long ago. Back at the Artai ruins, Yuna summons a Child resembling Kagutsuchi and both take flight.
Meanwhile, thanks to information provided by the Aswad, Arika discovers the Black Valley's current location. Both Yuna and Kagutsuchi arrive at the Black Valley and start attacking, Mai materializes her robe and does battle with Kagutsuchi while Yuna chases after Mashiro. Mashiro is eventually saved by the timely arrival of Arika, however Arika's powers alone are not sufficient to defeat Yuna. After a conversation with Ribbon-chan gives her an epiphany, Nina then reveals that the book she found in the ruins contains a Meister GEM, the Neptune Emerald, and requests a contract with Mashiro to assist Arika in defeating Yuna, Mashiro agrees and Nina materializes a new robe and element. Arika and Mashiro also eventually patch things up from their previous argument and Arika regains the ability to materialize her zwei robe.
While Arika and Nina fight Yuna, Otome from all over Earl are battling various Childs that have been spawned by Yuna, though to no avail as Yuna and the Childs seem to be able to regenerate their injuries by drawing power from the Shinso System. Nina tries using her Dash Cold Water Spout attack and manages to destroy one of Yuna's wings, only for it to rapidly regenerate. Thanks to information provided by Nagi, Natsuki broadcasts a plan to all Otome, since Yuna is drawing power from the Shinso System, Garderobe will sever the connection and activate the Surrogate System instead, preventing Yuna and the Childs from regenerating. However this only gives the Otome a window of 120 seconds to destroy Yuna and the Childs.
The plan works and Yuna's recently repaired wing shatters. However it lands right next to Mashiro, Yuna grabs Mashiro and absorbs her, causing it to change into a more poweful form. Despite this, both Arika and Nina successfully destroy Yuna and rescue Mashiro using their respective special attacks. The Childs summoned by Yuna elsewhere also despawn. Kagutsuchi is also defeated by Mai after she draws the sword from its head, causing it to turn into a kitten.
The series closes with all five who had been petrified returning to normal and Arika is shown flying with Mashiro in space heading towards the sunset as the credits roll. After the credits, Ribbon-chan is shown arriving at the steps of Garderobe declaring that she wants to be an Otome, a reference to Arika in the first episode of Mai-Otome.