“You really don’t know anything, do you, Ryuzaki?”
Maki Nikaido (二階堂 真希, Nikaidō Maki) is an elementary school student and daughter of Dr. Kimihiko Nikaido.
Maki is the daughter of the scientist Dr. Nikaido. His assistant Dr. Kimiko Kujo invented a virus 100 times stronger than Ebola and has an infection rate like that of the Influenza virus. Maki witnesses her father's murder at the hands of Dr. Kujo, who plans to use the virus to wipe out most of humanity. Maki runs away and ends up finding L, who takes her under his wing. Convinced that Maki has the antidote formula, Dr. Kujo tracks her down to L's headquarters.
Maki is a rather calm and polite girl who cares deeply for her family. In the novel, however, her personality is much different. She is somewhat of a troublemaker and rather bold, unafraid to assault a man holding an old woman at gunpoint.
Maki is also very protective of those she cares about, both her father and Dr. Kujo, often scolding Suruga and telling him to stay away from Dr. Kujo, who he has a crush on.
Maki, who was originally raised in Osaka, speaks in an Osaka dialect.
Maki has short, chin-length black hair and brown eyes. She keeps her bangs cut just above her eyes. She is commonly seen holding a patch-work teddy bear that has her mother's voice recorded in it. In the movie she is first seen wearing a school uniform, but later changes into a red dress.
Maki's past is elaborated on much more in the novel. It is revealed that her mother passed away, and before she died, she asked Maki to take care of her father. Maki is determined to do this, and does her best to take care of her father, even making him dinner.
Maki and her family are originally from Osaka, and they actually lived in the same neighborhood as Misa Amane prior to Misa's debut. Maki and Misa's families were close, the two families even used to go on vacations together.
Misa and Maki have a close relationship, Maki viewing Misa as an older sister, even after she became famous. Misa cares about Maki as well, going out of her way to help Maki escape, despite it being all over the news that Maki was carrying a deadly and highly contagious virus.
Maki is the daughter of the scientist Kimihiko Nikaido. When Dr. Nikaido was in his lab waiting for his assistant Dr. Kimiko so he can inform her something, a bio terrorist group appeared. Dr. Kimiko then arrived and admitted to him that she's the leader of the group. She tells him to hand over the antidote of the invented virus because she couldn't continue her plan to wipe out much of humanity without it. Dr. Nikaido refuses, and she threatens him, telling him that they'll see which is more important to him, Maki or the antidote.
Meanwhile, Maki arrives at the lab, and goes upstairs to find her father cornered by Kimiko and the bio terrorist group. She hides behind a wall and watches. Dr. Nikaido then takes out the antidote, and puts it somewhere where it will be destroyed. Then, he takes out the sample of the virus he got, and injects himself with it. While the virus takes effect, Kimiko pressed a button which causes electric sparks to fly around the lab. Maki, hidden behind the wall, watches as her father dies gruesomely.
Maki runs out to the car that she arrived with, and tells the driver to go to every address recorded on her phone. She cries all the way on the ride.
At L's headquarters, he receives a video chat with Kimiko telling him that she needs the antidote to the virus, and Dr. Nikaido was murdered by someone. Now she needs his help tracking it down. In reply, L tells her to meet him in his headquarters. After the chat, someone from the entrance of L's headquarters tells him that they need Watari. As it turns out, it is Maki's driver. Then, L, who later introduces himself as Ryuzaki, tells Maki that she can come into the headquarters.When Maki is there, Kimiko and the terrorists enter the headquarters and set off an alarm. Maki runs out of Ryuzaki's office and faces her alone. During their encounter, Maki injects herself with the virus, and was about to get shot. Ryuzaki rescues her from the terrorists and brings her and Near through a secret door in the hallway. While going through a couple of staircases, they meet an FBI agent who then helps them. L brings all of them to his pink truck that they use to escape.
The FBI agent drives Ryuzaki, Maki, and Near all throughout the town in the pink truck, drawing a lot of silly attention to themselves. Ryuzaki makes him stop at a market and he and the kids go inside. During their stay at the marketplace, Ryuzaki buys various things and makes a small transmitter that proves to be useful later.
Meanwhile, Kimiko is planning to track down Maki because of suspicion that she may have the antidote injected in her.
When a talk between Ryuzaki and the FBI agent is finished, the agent is once again stuck being the decoy, while Ryuzaki, Maki, and Near travel on the train to meet a scientist named Matsudo. While on the train, a television broadcast by Kimiko alerts the citizens that Maki is infected with a deadly virus. They get off at a stop, and cease using public transportation. In order to stay hidden, they ride bikes around the small town and Maki changes into a red dress so that people will not recognize her in her school uniform.When they arrive at Matsudo's lab, Ryuzaki tells him that they need him to create the antidote. After some persuasion from Ryuzaki, Matsudo accepts the job.
While making the antidote, Matsudo encounters many problems. After several failed antidotes, they arrive at a breakthrough. A drawing made by Near on a chalkboard lead Near to a conclusion: 13 and 11. Through that, Ryuzaki is able to figure out MK, which means Midkine. Midkine may be a significant ingredient to the final antidote.Maki has a picnic on the lab roof with Ryuzaki and Near. Ryuzaki and Near begin eating quickly, and Maki scolds them for not bowing and saying thank you before eating. After eating their food, Maki encourages Ryuzaki to try and stand up straight. After L successfully stands without hunching over, Maki and Near clap for him. With their picnic over, Maki says that she needs to use the bathroom. When Ryuzaki and Near are gone, she runs and leaves the lab by herself. At night, Maki arrives at a doc, where she had arranged for Kimiko to meet her there alone. Maki is kidnapped by the terrorists who end up taking Maki away for their experiments across the country. Ryuzaki runs to rescue her but is too late.
Ryuzaki returns to the lab, finding out that Matsudo had already finished making the correct antidote, but it hasn't been tested yet. Matsudo then makes many more, and Ryuzaki takes all of them. He and the FBI agent then go to save Maki, driving to the airport in the pink truck.
On the airplane, Kimiko has Maki in an operation room, but the captain of the plane tells the passengers that there's an unauthorized vehicle on the runway. Kimiko realizes that it's L's truck, and she takes Maki out of the operation area. At this time, one of the terrorists has already been infected by the deadly virus because of Maki's injection. The terrorists take out guns hidden in Maki's operation table. Kimiko commands one of the terrorists to take the plane off the ground. Ryuzaki's truck makes it just in time, and Ryuzaki jumps from the air-stair onto the moving plane.
Meanwhile, the passengers on the plane begin to be infected. The terrorist pilot of the plane dies, and the plane goes out of control. Kimiko starts to get infected as well. She thinks the plane will take flight, and the virus will spread. But Ryuzaki had also brought the transmitter he made earlier on with him, he says that its magnetic pull is strong enough to stop the plane.
As Kimiko dies, Ryuzaki injects the antidote into her, and tells a flight attendant to give everyone on the plane a shot of the antidote. Maki gets a shot before it was too late, and so did everybody else. L then runs to the plane's control booth, and stops the plane before it crashes into the airport.
Maki sees a knife laying beside Kimiko, and attempting to kill her, picks it up. Ryuzaki arrives just in time and convinces Maki to put the knife down. Maki tells Kimiko that it's okay, and she begins to cry. The ambulance arrives and takes the sick passengers away to the hospital.
At the end, Maki wakes up and finds her teddy bear with Ryuzaki's voice recorded in it. Ryuzaki says to her, "Welcome home Maki. Please have a good day tomorrow, too."
- “A peace that can only be gained by killing isn’t real! You’re no better than Kira!” (p 72)
- “I wouldn’t be happy living in peaceful world that was created by sacrificing people’s lives.” (p 108)
- (To Ryuzaki) “If we run, we run together! Besides, you’re the one who said you’d protect me. You said you’d take care of me until the end!” (p 113)
- “They’re so beautiful. I never thought about stars before, but now that I know I’m dying, they really are beautiful.” (p 123)
- (To Kujo) “What I have to do now is get you to live so you can redeem yourself, so you can atone for your sins.” (p 147)
- “Ryuzaki: Maki… should I hold our hand in this case?
- “Maki: Ryuzaki, in this case, you should shut up and hold it real tight.” (p 124)