Chihiro Furuya is a zombie-loving otaku who becomes depressed when his pet cat, Babu, dies after being hit by a car. Wanting to see him alive again, Chihiro looks into an old manuscript describing resurrection and starts doing experiments in an abandoned building. While there, he encounters a girl named Rea Sanka, who is depressed about how controlled her life is. When Rea learns that Chihiro had been eavesdropping on her secret rants, she decides to help him in his experiments, warming up to the idea that, if she were to become a zombie, Chihiro would take responsibility and look after her.

As Rea climbs up a cliff edge to retrieve a plant for Chihiro to use in his resurrection formula, she recalls how she had always been restricted by her father, Dan'ichirō, who showed obsessive levels of love for her and kept her from making any friends. She finds a hydrangea plant to use in the formula, taking a small sample of it herself before feeding it to Babu, though he doesn't appear to come back to life, prompting Chihiro to give up his experiments. As they part ways, Chihiro and his cousin, Ranko Saōji, discover that Babu has indeed come to life while Rea, punished further by Dan'ichirō, decides to drink the formula she stole in the hopes of killing herself.

As Rea awakens to find her suicide attempt has failed, she overhears Dan'ichirō plotting to castrate Chihiro. As Rea sneaks out in order to warn Chihiro, Chihiro chases after the resurrected Babu to a hydrangea field, where he spots Rea at the top of a cliff. As Dan'ichirō approaches her, Rea decides to stand against him before Babu climbs up there as well. As Dan'ichirō prepares to attack Babu, Rea takes the attack and is knocked off the cliff, tearing her stomach on a tree branch and dying as a result. However, because of the potion she drank, she comes back to life as a zombie.

Chihiro takes Rea back to his room, trying to keep her a secret from the others. As Chihiro goes out to apologize to Ranko, Rea has a brief encounter with Chihiro's grandfather, Jogorō. When Chihiro returns later that day, he finds Rea has become dazed and is showing signs of rigor mortis, bringing him to the realization that her corpse will rot if he doesn't do something soon.

As Chihiro tries to think of a way to preserve Rea's body, he hides her in his closet while he cleans the temple, where he hears from Jogorō that he was the one who originally made the resurrection potion. As Ranko looks in Chihiro's room for some DVDs, she is suddenly pounced on by Rea who starts fondling her. As Chihiro pulls Rea off of her, she grabs and kisses him.

As Chihiro tries to explain things to Ranko, Rea follows Babu to a field of hydrangea leaves and eats some, which helps her regain her senses and cure her rigor mortis. Jogorō explains to Chihiro that Rea needs to continue eating hydrangea leaves to avoid becoming a corpse, though mentions it is not a permanent solution. As Chihiro manages to convince his father to let Rea stay at their home, he begins recording his observations of her. As Chihiro and Rea take a walk that night, Rea ends up injuring Chihiro slightly while saving him from a car and begins curiously licking his wounds.

As Ranko gets Chihiro to help out with her family's deliveries, she recalls how she first met him and came to understand his obsession with zombies. After being saved by Chihiro from a stray dog, Ranko eventually came to fall in love with him. Back in the present, she attempts to kiss Chihiro but backs off and runs away, resolving to not lose to Rea.

As Chihiro continues his observations, Rea asks him to take her to the mall, unaware they are being tailed by some of Dan'ichirō's henchmen. As Chihiro goes to get some lunch, Rea is approached by Chihiro's classmate, Yasutaka, who tries to pull the moves on her. The henchmen move in to abduct Rea but she manages to fight them off with her zombie strength. However, the henchmen change their plans and abduct Chihiro instead, bringing him towards Dan'ichirō.

This episode, prior to the events of the previous episode, focuses on Chihiro's little sister, Mero. She and her classmates, Ichie Shinoda and Miko Yasaka, become curious about the strange actions of their teacher, Mizuki Yamanouchi, suspecting she may be a zombie. They soon learn Yamanouchi had been secretly keeping a pet crocodile and feeding it at school. Later, as they discuss stories about zombies, Mero recalls about her late mother who she remembered having cold hands. As she makes an offering to her grave, she runs into Rea, who ends up reminding her of her mother.

As Chihiro is strapped to a chair waiting for Dan'ichirō to call for him, he meets Dan'ichirō's wife and Rea's stepmother, Aria. Aria explains how she had joined the Sanka family as a maid in the hope of winning Dan'ichirō's love. However, Dan'ichirō instead fell in love with a sickly 15-year-old paraplegic girl who inevitably died after giving birth to Rea. Although Aria was eventually able to marry Dan'ichirō, he was more focused on Rea than her. Aria later learned the truth that Dan'ichirō's feelings for Rea are not because of fatherly love, but because of her resemblance to her mother. As Rea rushes towards the mansion, Chihiro is brought before Dan'ichirō, who becomes determined to protect Rea.

Dan'ichirō and Chihiro engage on a duel of fencing, and Rea arrives at her home looking for Chihiro. Dan'ichirō's maids capture her and started cosplaying her by maids. Using her zombie strength, Rea manages to escape and continues searching for Chihiro. At the fencing venue, Chihiro trash talks Dan'ichirō about being a nonsense father. Dan'ichirō, furious yet keeping his cool, pierces Chihiro and Rea suddenly arrives. Dan'ichirō was surprised of Chihiro's survival on the attack and Chihiro delivers a headbutt on Dan'ichirō. Dan'ichirō now intensely angry and attempts to slash Chihiro but Rea quickly parries Dan'ichirō's attack and reiterates her freedom. Chihiro lectures Dan'ichirō and reasons Rea's freedom. Impressed on Chihiro's words and promise, Dan'ichirō decides to let Rea stay on Chihiro and warns not to deflower her. After their conversation, Dan'ichirō left Japan and heads to America in search for the cure of Rea's ailment. Meanwhile at the Furuya residence, Chihiro wakes up and sees Rea wearing a nurse costume. Ranko arrives and introduces herself to Rea, posing as Chihiro's fiancee. Rea realizes based on the actions of Ranko towards Chihiro that she loves him.

As Chihiro is still trying to find a way to preserve Rea's body, Rea expresses interest in a fireworks festival. As Mero mentions to Chihiro about how Rea wants to go to school, rain cancels the fireworks festival, though Ranko suggests that they hold a smaller fireworks session at the shrine. As Ranko helps Rea change into a yukata, she confesses she is in love with Chihiro and wants Rea to be her love rival. As Rea decides to start going to school again, she suddenly enters a trance and jumps on Chihiro, biting his lip in the process.

Seven months before Chihiro first met Rea, he, his father, Mero and Ranko travel to Tohoku to help sort and move large book collection of father's brother. Along the way, they pass a bridge that seems familiar to Chihiro somehow, which leads him to question why he remembers so little about his mother, Yuzuna. Meanwhile, Rea, who had just finished middle school, faces abuse from Aria as she vents her drunken frustrations on her. As Chihiro helps clean up the books, he discovers a box containing a book about bringing back the dead. Despite being told it is worthless, Chihiro becomes interested in it and keeps it for himself. As Chihiro gets lost whilst trying to follow Ranko and Mero to a waterfall, he comes across an open air bath where he briefly encounters Rea before running off, which ends up smudging the book a little.

The episode is narrated from Babu's point of view as he describes life as a zombie. Rea attends her first day of school as a zombie, where her zombie strength helps her out. Meanwhile, Babu takes an interest in another female cat, but chooses to stop their relationship when he draws close to a confused state. Elsewhere, a scientist who studies zombies flies to Japan to see what new samples she will find, hydrangea leaves among her luggage.

As Aria feels lonely without Dan'ichirō, she falls asleep in the bath. Meanwhile, Chihiro and his family discover a strange girl lying under their temple, who doesn't appear to want to say a word to anyone. When Rea searches for her when it is time for dinner, she is pushed down the stairs. The next day, they discover all the nearby hydrangea leaves have been torn apart, and later that night Rea spots the girl making a move on Chihiro. As Rea suspects the girl of being behind the incidents, the girl hits herself to place blame on Rea. As Chihiro backs Rea up on her suspicions, the girl reveals herself to be Aria who rains hail down everywhere. The whole thing is perceived to be a dream by Aria, who fell asleep in the bath, and as a hallucination by Rea, who is surprised to find Chihiro had the same dream.