There is distorted, deep blackness everywhere. That place, in which blackness swallowed everything and took away everything, has become known as the Avidya Zone. Strange beings assume the very form of the despair and chaos of humanity. They are known by this name: Imashime. An expedition surveys the Avidya Zone which consumes human spirits. So, in the intricate intersection between the present in impending crisis and the destiny of the past … can eight boys and girls, assembled to confront the Imashime, find the bright future that lies before the Avidya Zone?

The protagonist, Chihiro Furuya, is a male highschool student with a keen interest in zombies, collecting zombie-related videogames, film and manga, and even to the point of desiring to “kiss a zombie girl”. Following the death of his pet cat, he attempts to revive it using an old manuscript, which describes the process of creating a potion for resurrection. At this time he encounters a girl named Rea Sanka, who has run away from home. In an attempt to commit suicide, she drinks a sample of the “resurrection” potion which is created from a poisonous herb known as Hydrangea macrophylla, however this fails to kill her. Following an argument with her father, she falls from a cliff by accident and dies; however as a result of the potion, she returns as a zombie. Though she becomes undead, she chooses not to consume human flesh, and rather survives on eating the hydrangea herbs.

Unaired episode titled "Nagarekawa, Annai Shite Mita." bundled with the Volume 1 Blu-ray/DVD.

Hentai! is a doujin anime made in MMD. Apparently it's about sex jokes.