Satou Matsuzaka is a beautiful high schooler who has a reputation for being permissive with men. However, a chance encounter with a young girl named Shio Koube makes Satou realize that this is her first and only true feeling of love. Telling others that she lives with her aunt, Satou secretly shares an apartment with Shio. Despite her innocent appearance, Satou is willing to do anything to protect her beloved, resorting to desperate measures to ensure that their "happy sugar life" remains intact. [Written by MAL Rewrite]

The world is in the midst of the industrial revolution when horrific creatures emerge from a mysterious virus, ripping through the flesh of humans to sate their never-ending appetite. The only way to kill these beings, known as "Kabane," is by destroying their steel-coated hearts. However, if bitten by one of these monsters, the victim is doomed to a fate worse than death, as the fallen rise once more to join the ranks of their fellow undead. Only the most fortified of civilizations have survived this turmoil, as is the case with the island of Hinomoto, where mankind has created a massive wall to protect themselves from the endless hordes of Kabane. The only way into these giant fortresses is via heavily-armored trains, which are serviced and built by young men such as Ikoma. Having created a deadly weapon that he believes will easily pierce through the hearts of Kabane, Ikoma eagerly awaits the day when he will be able to fight using his new invention. Little does he know, however, that his chance will come much sooner than he expected... [Written by MAL Rewrite]

A video blogger attempts to fake cryptid sightings to boost his views, but gets more than he bargained for when his crew is slaughtered by a real monster. Elsewhere, students find themselves preyed upon by a sandworm-like beast, initiating a desperate struggle for survival on their own school grounds. With more of these attacks from mysterious creatures occurring, researcher Sousuke Banba tasks himself with delving into the mystery. With nothing but the keyword "Kagewani" to lead him, he scours the sites of recent attacks in hopes of finding a lead to eradicating the creatures for good. However, Sousuke finds that these threats to humanity are even closer to home when the pharmaceutical company, Sarugaku, starts to encroach on his investigation. [Written by MAL Rewrite]

After surviving the onslaught at Sarugaku headquarters, Sousuke Banba resumes his investigation of the Kagewani monster hybrids. Armed with the ability to harness the Kagewani's power, the researcher now has a means to eliminate the creatures. But despite the benefits of this skill, it has one major drawback: Sousuke now struggles to maintain his sanity, with the power threatening to consume his body. Soon, threats old and new begin to rear their heads, as the upper echelons of Sarugaku become active once again and an assassin with a personal vendetta sets her sights on Sousuke. Nevertheless, he resolutely forges ahead on his mission, determined to track down the origins of the Kagewani and eliminate their threat once and for all. [Written by MAL Rewrite]