In an apartment building in Tokyo, Akira is running from a horde of vicious flesh-eating zombies. However Akira is more worried about getting to the office in time rather than scared for his life. This all started a year ago with Akira's first job.
When Akira joins an advertising company, he’s still full of dreams and enthusiasm. His colleagues greet him warmly and even throw him a little welcome dinner at a restaurant, and Akira immediately gets a crush on his senior colleague Ohtori, making him think that this might be the best workplace ever. However his illusion gets shattered quickly when on the very first day he must pull two all-nighters consecutively and return home almost as a living corpse.
From then on, Akira’s situation only gets worse every day. His exploitative boss Kosugi wrings the ever-living life out of him with his insane workload and soon the office becomes Akira’s home because he doesn’t leave most of the time. Since he needs the money he can’t even think of quitting, and Akira slowly becomes a working zombie that loses his free will under the toxic environment of his workplace.
Only his crush Ohtori treats him with kindness, but when Akira shares his admiration for her work ethic and the fact that she seems to be doing what she loves, Ohtori says that isn’t the case for her either and that what they really want to do just falls to the wayside. One evening, Akira manages to get a bit of free time to go out to dinner with his best friend Kencho, who used to play football with Akira during college. Kencho thinks Akira should quit and calls him a corporate dog, in return Akira reminds Kencho of how they lost the big games in college because of him.
An argument ensues and the friends part in bad terms. Eventually Akira falls into a deep depression and his apartment becomes a trashy mess. Sometimes when he’s at the train station, he considers ending things for himself.
A year after Akira started working in the office, he finds his neighbor on the ground outside. However when the man turns around, Akira realizes the guy has become a zombie and he’s in the process of eating another neighbor. Terrified, Akira begins running upstairs as more and more zombies show up to chase after him, sometimes coming out from the other apartments.
Worrying about being late, Akira makes it all the way to the roof and jumps over a fence to leave the zombies on the other side. While a plane on fire flies by to crash in the distance, Akira watches the chaos that has taken over the city and realizes something: he doesn’t have to go to work. This causes him so much happiness that he does a little dance, wondering what to do with his new free time.
At that moment he remembers Ohtori and sends her a message to check if she’s ok, in return she sends him her location asking him to come over. Then Akira leaves the building by climbing down a pipe. Through an open window, he sees a pregnant woman and her husband, and he promises to come back with food for them before he continues climbing down.
Using his bicycle, Akira manages to go fast down the road, dodging every zombie that tries to get him. Moments later, he makes it to Ohtori’s apartment and finds her so terrified that she clings to him. At that moment, Ohtori reveals she’s been having an affair with the company director, who is there right now and he’s already become a zombie.
The director immediately attacks, but Ohtori can’t move because her leg is wounded, so Akira begins fighting the zombie. After some struggle, Akira uses his football training to tackle the director, throwing him against the furniture. Ohtori takes this chance to hit the zombie until he dies while yelling at him for not leaving his wife like he had promised.
Suddenly Ohtori falls to the floor, and after a short seizure, her body transforms into a zombie too. She tries to attack Akira, but he doesn’t hesitate to push her away before she can bite. Then Akira confesses his feelings for her before running away, closing the door behind him to stop her from following him.
In the evening, Akira returns to his building with lots of supplies, but when he stops by the neighbors’ place, he finds it empty and covered in blood. He returns to his apartment in tears, but as he grieves for his neighbors, he remembers Ohtori telling him that what they really want to do always falls to the wayside. Akira realizes he may die soon and that he doesn’t want to go without having done what he really wants, so he grabs a notebook and starts a list titled “100 things to do before becoming a zombie”.
The first one is telling someone he loves them, and he already crosses it off the list. The next morning, Akira wakes up with lots of energy and begins working on the list. First he cleans his apartment, then he goes to the supermarket to get all the expensive things he never got to buy before.
There are a few zombies here, but he escapes from them by riding the trolley. Next he dyes his hair, but after trying a few different colors, he decides to stick to his natural black. He also paints his portrait on the side of a building and finds a bike that he drives through the city at full speed.
In the evening, he lits a bunch of fireworks next to the Tokyo Tower to celebrate his new life. Days pass as Akira continues to come up with things for the list. On the fifth day, he has a barbecue on the roof of his building while ignoring the zombies on the other side of the fence.
When he’s about to have his steak, he realizes he ran out of spices, so he goes to the supermarket to grab some. Suddenly he hears a noise and a person with a helmet shows up to start beating him up, only stopping when Akira points out he isn’t a zombie. Then the person takes off the helmet and Akira is shocked to see a beautiful woman named Shizuka.
While they’re chatting, they suddenly hear a man asking for help outside. Akira rushes out to throw things at the zombie chasing the man, but it’s not effective. The zombie enters the market and Shizuka begins fighting him, showing off amazing skills.
When a second zombie comes, she just keeps him away by throwing a little alarm device, revealing that the zombies are attracted to sound. Akira is impressed and invites Shizuka to stay with him but she turns him down, explaining that Akira’s need to save people will only attract danger. Afterward, Akira returns to his apartment, and looking at pictures of his college days makes him worry about his friend.
He decides to add something to the list and then he calls Kencho, who is still human but in trouble. He’s stuck inside a love hotel room because the corridors are full of zombies and the girl he had tied up to do the naughty is infected too. Akira promises to rescue him and after putting off his old football uniform, he leaves on his bike, dodging all the zombies on the streets at great speed.
Some zombies tried to hold onto the back wheel, but Akira loses them with a sharp turn. Meanwhile Kencho tries to leave the room, only for a zombie horde to immediately come after him. He rushes back inside but hearing the zombies slam the door makes him have flashbacks of the time he failed the big game, putting him on the edge of a breakdown.
Back to Akira, he finds the street of the hotel full of zombies, so he throws a speaker on the ground and makes it play music, causing all the zombies to gather around it. Then Akira uses his football training again to dodge and jump over any remaining zombies, even pushing a few of them away. After jumping on the roof of a few cars, he manages to enter the hotel and tackles another zombie before searching for Kencho.
In the room, Kencho suddenly realizes it’s quiet and opens the door to find the corridor empty. Akira shows up and both friends apologize to each other before more zombies come after them. The guys immediately run to the roof and jam the door with a ladder, finally getting to escape.
The duo hides in a fancy restaurant and shares an amazing meal, during which Kencho finds the list. He discovers the last item is “making up with my best friend” and tells Akira that he’s grateful for having him protecting everyone. This inspires Akira with an idea: he now wants to become a superhero to rescue people from the zombies, but Kencho points out Akira doesn’t have powers.
Sometime later, Kencho sees on the news that Tokyo is becoming hell on Earth and says they should leave. Akira agrees and chooses the Marine Paradise Aquarium in Ibaraki as their destination because they have a special diving suit that protects the body from sharks, so it should protect Akira from zombies and be his superhero suit. Afterward they go to a market to get supplies, but at that moment they see a group of people running away from the zombies.
Most of them unfortunately get killed, but Akira manages to get the attention of two flight attendants, a bus driver, and Shizuka, whose skills can’t protect her from such a huge horde. The group runs into the store and pulls down the shutter, cutting a zombie's hand in the process. Everyone is grateful for the rescue, but the bus driver hides his bitten hand.
Then they grab a bunch of supplies and have a little dinner with lots of drinking. Akira’s list includes “have a drink with a flight attendant”, but when he tries to flirt with them, they ignore him in favor of Kencho. Both women leave with Kencho to get naughty in private, and Akira tries to chat with Shizuka, who notices he cut his hand with the shutter.
She immediately takes care of it, revealing she used to study to be a doctor. At that moment, the bus driver transforms into a zombie and starts chasing after Akira and Shizuka. However when he hears the trio having fun, he decides to go after them instead.
By surprising them from behind, the driver manages to tackle one of the girls and bite her. When her friend tries to help her, the driver just turns to her and bites her too. Next the driver begins chasing Kencho, and when Akira wishes to help him, Shizuka decides to leave them behind because she’s better at surviving on her own.
However Shizuka finds a radio and uses it to distract the zombie, giving Akira the chance to rescue Kencho. While the driver is stuck on the radio, Shizuka runs to the door, but she can’t lift the shutter alone and soon the zombified girls find her. She uses a basket to push all the zombies away while the boys show up to lift the shutter too, but they can’t open it either.
Seeing Shizuka fighting all the zombies at the same time, Kencho rushes to lit a bunch of fireworks, which distracts the zombies and allows Akira to rescue Shizuka. Then trio works together to open the shutter, and the boys rush to get inside an RV. At first Shizuka doesn’t want to join them, but seeing the zombies come after them and considering she can’t drive, she has no choice but to go with them.
Soon the trio is out of the city. Their destination is the aquarium, but they still stop often to do all kinds of things like freeing dogs from their leashes, gathering supplies, and Kencho even dyes his hair. Akira asks to do things from his list like sup yoga, which ends with Kencho falling into the water.
They also go paragliding, cook on a campfire, and lit more fireworks. When they come across a hotel with hot springs, they ignore the zombies and spend the night there. They enjoy the warm water, the hot sake, and a wonderful view of the sky filled with fireflies.
The next day, the trio finally makes it to the aquarium, but the RV suddenly goes off the road and crashes, causing Akira to lose consciousness. It’s then revealed that the road is covered with spike trips. Moments later, Akira wakes up to a voice yelling his name, and he’s shocked to discover his old boss Kosugi is there.
It turns out all the survivors from Tokyo are hiding here, including Akira’s neighbor couple. They’ve formed a community and now work together to survive inside the aquarium, which has become their fortress. The survivors are divided into teams to take care of the different chores, and Kosugi is the leader of the community that keeps everyone on their toes.
They also have a few trucks that sometimes leave for the city to gather supplies, and to stop other people from robbing the vehicles, Akira is surprised to see they use zombies. There’s a bunch of them outside locked behind fences, and when they need them to move, a guard uses a megaphone to get their attention. Kencho and Shizuka are already helping with the work, and Kosugi asks Akira to join them too.
Akira hesitates because he wants to finish his bucket list, but Kosugi makes him stay by pointing out this is safer for his friends. Later over dinner, Kencho is furious to notice that Kosugi and his close buddies eat luxuriously while all the other survivors only get controlled rations. To make matters worse, the boss’ group treats Akira like a servant.
Kencho wants to fight them, but the husband stops him because misconduct can get the whole team kicked out. Then Kencho and Shizuka share their food with the pregnant woman so the baby can be healthy. To thank them, the husband shows Kencho and Shizuka a way to sneak out to reach the parking lot.
Kencho checks on the RV, but the tires are ruined. Akira continues to work hard, but he soon feels like he’s being a zombie slave again. Meanwhile in the city, a truck driver is distracted while having a smoke and doesn’t see a zombie getting inside the truck with the supplies.
Later the truck returns to the aquarium and as soon as the driver opens the door, the zombie jumps out and bites him. The guard tries to run away and with the door open, a horde of zombies begins making its way inside. Chaos soon takes over the aquarium as people run like crazy and the zombies begin biting every survivor they can put their hands on.
Soon some of the zombies reach the shark exhibition and fall into the water where they all become shark food. In the meantime, Kencho and Shizuka show Akira that they’ve fixed the RV and stolen some supplies, so they can leave. However Akira points out that this place is safer and decides to stay.
While Akira goes back inside, Shizuka finds the bucket list and after seeing all the activities they’ve done together, she notices that “becoming a superhero” hasn’t been crossed out yet. Inside the aquarium, Kosugi is yelling at everyone because he’s noticed there are people missing and work needs to be done. Suddenly Kencho pulls him back and Shizuka cuts in to talk to Akira, pointing out that living like this isn’t really living, they’re just zombies without the bite.
She also shows Akira his bucket list, causing him to remember how much he had hated working for Kosugi and how much he had loved having fun in the middle of the apocalypse. Suddenly Kosugi steals the list and throws it on the ground to step on it, which finally makes Akira react. He pushes Kosugi to the ground and retrieves the list before announcing that he quits.
At that moment, zombies finally reach this area too and chaos ensues. Kosugi pushes his buddies off before running away, but Akira tries to guide people out with the help of his friends. They run through the corridor and lock the door behind them before making their way into the shark exhibition room, where they find Kosugi.
A furious Kencho grabs him and calls him out for abandoning his people, only to be interrupted by a shark jumping out of the water and landing next to him. People panic but Shizuka tells them not to worry, since sharks can’t move on land. However the shark suddenly releases all the legs of the zombies it ate, allowing him to walk on the floor.
The group runs back to the corridor, only for the shark to block the way by smashing through the wall. Everyone begins running again and Kosugi decides to hide while Akira finds a door and takes everyone inside for safety before locking the door. While the shark bangs on the door, Kosugi tries to sneak out, but he makes a noise and gets the attention of the beast.
At the same time, Akira realizes Kosugi is missing and says he wants to help him, causing Kencho to point out that Kosugi deserves what he gets. However Akira doesn’t want anyone to die under his watch. Since he can’t stop him, Kencho helps his friend instead by revealing that there’s a special diving suit in the room.
Meanwhile Kosugi is running down the corridor and trips. When the shark is about to get him, Akira shows up in his new superhero costume and kicks the shark, only for the beast to jump on him to attack. Akira holds onto the shark’s mouth but instead of helping him, Kosugi runs away.
Luckily Kencho shows up in a forklift, so Akira gets out of the way to give him space. Kencho drives the forklift right into the shark, but after some struggle, he realizes it’s not making any damage and decides to run away. When Akira reaches the shark exhibition, he finds Kosugi surrounded by zombies and immediately jumps in to fight them.
He manages to defeat a few, but there are too many and soon he’s surrounded. The zombies begin biting him and although they can’t break the special suit, it’s still painful for Akira. In the corridor, Kencho is running from the shark, and when he sees the hole in the wall, he decides to jump through it to enter the exhibition.
The shark tries to follow him, but it’s too big and gets stuck in the hole. Suddenly some music starts playing: it’s Shizuka, who has brought two megaphones to distract the zombies. With quick and elegant movements, she runs through the horde as they come after her and when she reaches the edge of the tank, she throws the megaphones behind her.
This causes all the zombies to follow the noise and fall into the water. The trio reunites and when Kosugi tries to join them, the shark finally frees itself and pushes the boss away. Akira rushes to check on him and the shark tries to attack, but Akira uses a piece of pipe to keep its mouth stuck.
However the shark is stronger than the pipe and closes its mouth anyway, capturing Akira’s hand. As the shark begins whipping Akira around, Shizuka rushes to grab a flashlight to get its batteries, explaining that sharks have an ultra-sensitive tool for detecting their prey in their heads and that a jolt of electricity could kill it. After Shizuka connects the batteries with tape, Kencho grabs them and remembers the football pass he failed in college, concentrating to do better this time.
The batteries are thrown with all of Kencho’s strength and land safely on Akira’s hands right before the shark turns to Kencho and hits him hard. Furious, Akira holds the batteries in his fist and jumps to punch the shark right on the nose, sending a jolt through its body that effectively kills him. Afterward Akira and Shizuka rush to check on Kencho, who turns out to be just fine.
A few hours later, all the survivors have distributed the supplies among them and are getting ready to leave the aquarium. Kosugi shows up to try to stop them, but now the families are ready to stand up to him, and even his old employees call him out for having always been an awful boss. Everyone agrees Akira had been a better leader and now they’re ready to leave to have a real life instead of working like a zombie.
Ignoring Kosugi’s whining, all the survivors thank Akira for opening their eyes and they leave in the cars. When the trio gets in their RV, Kosugi pretends to regret everything and tries to join them, but they turn him down and leave without him. Now the three friends are ready to add more things to the list: Shizuka wants to be a doctor to save lives and Kencho wants to be a comedian to make people laugh.
Akira crosses out “being a hero” and adds “making being a hero his new job” before announcing they’ll keep going until they reach 100.
