The Goddesses and their sisters take a break from the hustle and bustle of nation-ruling with a quick camping trip to "My Summer Vacation Mountain." When Nepgear, Uni, Rom, and Ram go for a walk, they pass through a series of shrine gates and...end up in another dimension?!​​

There they meet someone that looks like an older version of Neptune! What shenanigans will ensue, and can the sisters ever get back home? Are two Neps better than one?​

[Source: Idea Factory Intl]