Valkyrie Drive isn’t just a Vita game but a multi-media series in Japan, with it getting its own anime series. This series has a different cast compared to the games but they came to the game after its Japanese launch. When asked about this content for the western version, P-Qube games was happy to answer this question.

PQube has revealed the release date for its anime character DLC, and has released the launch trailer for the latest Kenichiro Takaki title to get the localization treatment.
First up we have news regarding the availability of the Japanese-released Mamori and Mirei character DLC, which comes by way of the even more raunchy Valkyrie Drive: Mermaidanime. Thanks to an inquiry by Twitter user @Ravjeet_Bagal, it looks like the DLC will hit the West on October 14th.
https://twitter.com/PQubeGames/status/782289312826130432?ref_src=twsrc%5Etfw

In addition to this news, a launch trailer released for the title but keep in mind this is for mature readers only, as the game is rated M.
Source: The Vita Lounge