以主人公安久为轴，描写战斗少女们的群像剧。故事讲述了掌握了高端情报技术“玛娜”的人类，借助它的力量克服了地球上的战争、饥饿、污染等问题，终于迎来了和平的理想乡。然而，作为皇国第一皇女的安久丽莎，却因无法使用这等魔法之力而沦为士兵，并被派遣到偏僻的岛屿上，同其他少女们操纵变形人型兵器“帕拉美露”，共同对抗入侵而至的巨大攻击型生物——龙。于是，少女的不屈物语就此开始了……

It has been several centuries since human population has declined. Food has become harder to find and what little sources the humans have are considered highly valuable. The most prosperous species on the Earth are "Fairies", 10 cm tall creatures with high intelligence and a great love for sweets. A nameless girl, the main character, became a UN arbitrator between the humans and the fairies and had returned to her hometown to help her grandfather. One day, the village is sent some strange products made by a company called FairyCo. Since the villagers are wary of using the products, the girl, her grandfather, and a nameless boy decide to go to the factory to find out about the mysterious products and who is behind making them.

After moving into the quiet town of Hinamizawa, Maebara Keiichi spends his days blissfully in school often playing games with his local friends. However, appearances can be deceiving. One fateful day, Keiichi stumbles upon news of a murder that had occurred in Hinamizawa. From this point on, horrific events unfold in front of Keiichi, as he soon learns his close friends may not be all that they seem.

So exactly what’s going to happen when Hachiman Hikigaya, an isolated high school student with no friends, no interest in making any and a belief that everyone else’s supposedly great high school experiences are either delusions or outright lies, is coerced by a well meaning faculty member into joining the one member “Volunteer Services Club” run by Yukino Yukinoshita, who’s smart, attractive and generally considers everyone in her school to be her complete inferior?