超次元游戏 海王星 ～涅普的暑假～

Arriving at the lush, nature-filled "My Summer Vacation Mountain," Neptune and her companions decide to enjoy a vacation there. For the first time in a while, the four goddesses of the nations are all together, engaging in their usual lively banter. Amidst this, Nepgear heads out to explore the mountain with Uni and the other little sisters. Along the way, after passing through a long series of large torii gates, the little sisters somehow end up lost in another dimension... There, Nepgear encounters a woman who looks exactly like her older sister, Neptune—but in an adult form.