Kojo Akatsuki is an ordinary high-school boy—but when that high school is in the Demon District of Itogami City, "ordinary" means something rather different. He might be a vampire, for example. He might even be the most powerful vampire of all time. Middle schooler Yukina Himeragi, meanwhile, is the attack mage sent to observe him—a cute girl sent to observe a massively powerful vampire boy whose abilities activate whenever he gets aroused, on an island city full of all manner of supernatural individuals, each with their own shadowy agenda... What could possibly go wrong?

Yukina is trapped in a pitched battle against Astarte the homunculus, and she's losing—when who should come to her rescue but the very boy she's been assigned to observe, Kojo Akatsuki! Akatsuki tries to end the clash, but Astarte's familiar, the fearsome Rhododactylos, isn't going to let that happen. Is this a fight that only an awakened Fourth Primogenitor can finish?

At the invitation of Dimitrie Vattler, emissary of the First Primogenitor, Kojou and Yukina attend a yacht party. Dimitrie's guardian has it in for Kojou, and as though that's not bad enough, the festivities turn serious when Kojou and Yukina discover a terrorist plot that threatens Itogami Island itself...

Asagi, Yukina, and Nagisa have been captured by the Black Death Emperor faction. Kojou and Sayaka go after them, breaking into the island they suspect of being the terrorists' base. But an ancient terror awaits them—the Nalakuvera. A new beast vassal stirs within the Fourth Primogenitor, but will Kojou's power be enough to save his friends?

Yukina and Koujou are reunited once more and ready to take on the army of Nalakuvera! Will the strength of his new beast vassal allow the Fourth Primogenitor to reign supreme, or will the Black Death Emperor Front succeed in destroying Itogami City?

After partnering with Natsuki Minamiya to capture the Masked and end the destruction in the sky, Kojou and Yukina are shocked to discover one of the winged girls is none other than Yukina's classmate Kanon Kanase! When Kanon disappears, Kojou and Yukina seek out her adoptive father, a researcher at megacorp Magus Craft, Inc. Far from the professional meeting they expected, the two find themselves abandoned on a deserted island! It is deserted...isn't it?!

Time is running out for Kanon Kanase. If they can't stop the faux-angel ritual in time, she'll ascend from realm of mankind and become something truly inhuman. Will the Fourth Primogenitor be strong enough to stop this madness before it's too late? The Amphisbaena arc reaches its heart-pounding conclusion!

An alchemist repeatedly raids various places to get the liquid-metal lifeform—Wiseman's Blood. Blood spirals out of control in Strike the Blood's ninth manga volume!

It's a battle to the death between the complete human and the strongest vampire! The Wiseman had been using Kou Amatsuka to bring about his own revival. When he attacks a ferry, can Nina Adelard obtain La Folia's cooperation in order to save them?!