Valkyrie Drive: Mermaid - Season 1 - Eps 1: I'm Getting Deflowered
Mamori Tokonome, a girl who was diagnosed with an irregularity in her body, is captured by agents and taken to a remote island known as Mermaid. There, she is attacked by two girls named Miyasato and Kouzuki, the former being a Liberator who arouses the latter, an Exter, to transform her into a gun known as a Liberator Arm. Just then, another girl by the name of Mirei Shikishima arrives on the island, protecting Mamori by transforming her into a sword, allowing her to defeat Miyasato and Kouzuki and escape to the jungle. Arriving at a white castle, Mamori and Mirei are trapped in a colloseum, they are confronted by another Liberator, Saejima, who uses one of her masochistist slave girls to bring out a ball-and-chain Liberator Arm. Just as the two are cornered, Mirei once again uses arousal to transform Mamori into the sword Liberator Arm, allowing her to defeat Saejima in an instant.
About Valkyrie Drive: Mermaid

Title: Valkyrie Drive: Mermaid
First Air Date: 2015-10-10
Last Air Date: 2015-12-26
Status: Ended
Rating: 7/10 (from 34 votes)
Language: JA
Seasons: 2
Total Episodes: 12
Network: AT-X Tokyo MX Sun TV TV Aichi BS11 KBS Kyoto
Genres: Animation, Action & Adventure
Production Companies: ARMS
Synopsis
Tokonome Mamori is transferred to Mermaid - an artificial quarantine island for people with superpowers. When Mamori is attacked, a newly transferred girl named Mirei saves her. The enemy doesn't stop, however, and the two are soon cornered. Just when they think all hope is lost, Mirei kisses Mamori, and Mamori turns into a sword. Mirei then wields the sword and launches a counterattack against their enemies.
Cast

Yuka Iguchi
Mirei Shikishima

Mikako Izawa
Mamori Tokonome

Yuna Yoshino
Akira Hiiragi

Asami Seto
Charlotte Scherzen

Azumi Asakura
Lady J

Masumi Tazawa
Kasumi Shigure

Yurika Kubo
Meifon Sakura

Hitomi Harada
Momoka Sagara

Saori Onishi
Rein Hasumi

Kikuko Inoue
Torino Kazami