~§~ Valkyrie Drive: Mermaid ~§~
           There’s a mysterious virus known as the A Virus (Armed Virus) infected a small a small percentage of the girls’ population. There are two divided group classes, one is the Extars, who can transform into weapons when they get sexually aroused, and the other class is Liberators, who have the power to wield an Extar's weapon form, also known as Liberator Arms, through a process known as Drive. With the girls being afraid of the power they now hold; the girls are sent to islands where they spend their lives away from the rest of the world until the islands' Observers decide when they are ready to rejoin society again.
           Mamori Tokonome is a naïve 16-year-old girl who is use to being teased at school because of her name having a surname that can also be read as “virgin.” Little does she know she will have to get use to being teased in other ways. Mamori gets kidnapped and stranded on an island called, “Mermaid.” Luckily, a girl named Mirei Shikishima knows how to take the lead, through a kiss, she unleashes Mamori's Exter transformation abilities, turning her into a sword through the power of arousal. The two of them must do what they can and try not to get killed on their adventure to get back home before Warter can claim them for good.