謎の化け物の出現により瘴気に侵された世界。
対抗できるのは聖母と呼ばれる生体兵器だった。
――これは、美しき少女たちの悲哀の物語。
The girl flies. To take her revenge. The Earth has been consumed by a miasma caused by the appearance of a mysterious monster. The only thing that could fight it was a bioweapon called the “Mercy”. ――This is a sorrowful story of the beautiful girls.
