In the year 1923, a vampire crisis takes Tokyo by storm. Provoked by the illegal trade of Ascra, an artificial blood source, the population of vampires begins to rapidly increase within the city. Under orders from Lieutenant General Sounosuke Nakajima, the Special Forces Unit 16 gathers vampires within the military to create a new undercover vampire-hunting unit known as Code Zero. Leading the unit is Colonel Yoshinobu Maeda. Responsible for locating the source of the Ascra trade as well as capturing and killing vampires, he is pressured into producing fruitful results amidst the growing criticism that threatens to decommission the unit. To make matters worse, the vampires within the unit are struggling to grasp their newfound powers and identities now that they are no longer human. With the world at odds against them, the members of Code Zero must find a way to curb the crisis or otherwise fall victim to their own demonic natures.

In the 1920's, Inaho resurrects a vampire named Mosquiton with her blood. He awakens and becomes her slave. Now, Inaho is after the O-Part, which will grant her immortality. However, a bunch of supernatural monsters are out to stop them from achieving their goal. (Source: ANN)

Apparitions, oddities, and gods continue to manifest around Koyomi Araragi and his close-knit group of friends: Tsubasa Hanekawa, the group's modest genius; Shinobu Oshino, the resident doughnut-loving vampire; athletic deviant Suruga Kanbaru; bite-happy spirit Mayoi Hachikuji; Koyomi's cute admirer Nadeko Sengoku; and Hitagi Senjougahara, Koyomi's eclectic girlfriend. A new semester has begun and with graduation looming over Koyomi, he must quickly decide the paths he will walk, as well as the relationships he will form and friends that he will save. But as strange events begin to unfold, Koyomi is nowhere to be found, and a vicious tiger apparition has appeared in his absence. Hanekawa has become its target, and she quickly finds she must fend for herself.

Shido Tatsuhiko is not only a private eye... he is also a vampire with no real memory of his past. Joined by Yayoi Matsunaga, a female government agent, Riho Yamazaki, an orphaned teenage girl working as his girl Friday and Guni, a little green imp, Shido must face demonic creatures known as Nightbreed. Meanwhile, Cain, the vampire who made him what he is now, is seeking him... (Source: ANN)