Nakayama married her husband, Henry Nakayama, in an arranged marriage. She was originally promised to Hideo Furuya, but manipulated affairs to end up with Henry instead, having heard of Hideo's lack of honor. She is deeply rooted in the traditions of Japanese culture, but also bent towards superstition, such as sprinkling rice to ward off evil spirits. She may have a secret in her past which is connected to the hauntings occurring within the Japanese internment camp that she and her family have been sent to in the wake of World War II. She is a very dignified individual, apologizing for the mess even after being forced into a filthy cell.
Losing a sister, adopting a son
She was saddened to hear of the suicide of her sister, Yuko Tanabe, who traveled to Terminal Island as a picture bride for Hideo Furuya. She was originally to be married to Hideo, but upon learning of Hideo's lack of honor, arranged affairs so that she would marry Henry Nakayama instead and her sister would marry Hideo. ("Come and Get Me") Upon learning that her sister had a child, Taizo, that she had surrendered to an orphanage, she too traveled to the United States and adopted the child. Shen then married Henry and together they named the child Chester Nakayama. They raised him to adulthood, never once even hinting to him of his true origins. ("Taizo")
She is shocked when she finds out that her son has been dating a Mexican-American woman, Luz Ojeda, and she is pregnant with his child. Nevertheless, she does her best to be welcoming to Luz. Her husband is sent to a prison camp in South Dakota where he is forced to endure hard labor and freezing conditions. She is not made aware of his location. ("All the Demons Are Still in Hell")
She and her family are sent to the Colinas de Oro War Relocation Center, a Japanese internment camp, though her husband remains at the prison camp. She dreams of waltzing with him to a Duke Ellington tune and is wakened by Amy Yoshida, who tells her that her husband is there at the camp. It turns out he was released, but he is in a bad state, his feet in particular badly frostbitten. He also shuns Chester's girlfriend, Luz, whom she has been helping to take care of. She puts up a paper, and ofuda, to ward off evil, but Henry tells her that it can't ward off human evil, spies that are always listening and watching. When her son Chester leaves to join the Japanese Linguist Program as a translator, she cuts off a lock of his hair, which she could use to cremate in order to give him a proper burial if he didn't come back. Later, when Luz asks her if there was someone she could see in regards to her pregnancy other than Dr. Kitamura, who had shunned her, she recommendes a new midwife in one of the barracks. The midwife turns out to be Yuko Tanabe, a yurei, or undead spirit, who had been haunting the camp. ("Gaman")
She admires a picture sent to her by her son of him in his new army uniform. She asks Luz about her baby and is pleased when she allowed her to feel her belly. Later, she and the other members of the Nakayama and Yoshida families are disturbed to learn that she is carrying twins, as this is considered a bad omen in Japanese tradition. Despite this, she tries to act happy about the news, but nevertheless warns her to not inform Chester until after the babies were born. Ultimately, however, Luz's two children, Enrique and Hikaru, aere stillborn. Asako joins the others in praying over a memorial to the two lost children. Luz asks her to find Yuko and tell her what happened. She tries to, but finds the barracks where Yuko is supposed to be living empty, containing only a solitary lantern and some hair on the floor. ("The Weak Are Meat")
In the months following the loss of Luz's children, she and her husband care for Luz as she falls into a despondent state. They see her off when she leaves the camp with her father, Bart, after receiving the news that her brother Dennis was killed in the war. ("Shatter Like a Pearl")
A truth revealed
Chester returns to the Colinas de Oro War Relocation Center following a medical discharge from his work as a translator in Guadalcanal and an accident in which he wrecked a Jeep. She confronts Fumi Yoshida when she harangues her son, telling him that a spirit follows him, one which killed her husband and killed his children as well. She tells her that her son is a war hero and sends her away, but Chester says that she's right, that a spirit does follow him. The spirit caused the accident and came after his children. He demands that that she explain more about what Fumi was saying. She hugs him and her bones crack strangely, veins popping in her face. She says that she's missed him and tells him to find his woman, that their bloodline must continue. Chester realizes that she's been possessed by the yurei, Yuko Tanabe. He calls her a demon and demands that she get out of his mother. She's surprised to hear him call Asako that. She starts to choke Chester, but when a crowed begins to gather, she releases Asako, who falls to the ground.
Later, Chester gets the truth out of her and Henry. He is not their birth child, but rather the adopted child of Yuko Tanabe, who was Asako's sister. Asako explains that she was still in Japan when she learned that her sister had committed suicide. She could not bear the idea of her sister's child being raised in an orphanage, so she made the crossing to America to raise Chester. Chester is disgusted that they would raise him his entire life and never say a word. He disowns Henry right then, but seems to have some sympathy for Asako, calling her his blood. That night, the family burns Yuko's body in a ceremony, so that she'll have no place for her spirit to go. Asako objects at first, but then agrees it must be done. ("Taizo")
In the wake of these revelations, Chester shuns both Asako and Henry, not talking to either of them. They respond by instead spending their time and attention on Toshiro Furuya, who has been living with them following the death of his father Hideo. When Chester is sent to Tule Lake for attempting to escape from the camp, Major Bowen asks him if he has anything to say to his parents, but he replies that his parents are dead. Asako watches sadly as the transport takes him away. Later, she worries over Chester when he hears that he attacked the soldiers who were transporting him and escaped by jumping into a river. Both she and Henry, however, are consumed by caring for Toshiro, who is one of the many victims of a lung illness that has swept through the camp. ("My Perfect World")
In January 1945, she and her husband are granted sponsorship by Corbett Delaney to leave the Colinas de Oro War Relocation Center so that Henry can become his gardener. Their application is accepted and they are given $25 apiece as well as tickets home. Asako worries that Chester might return to find them gone, but Henry dismisses her concerns, feeling that they don't owe anything to such an ungrateful son. ("My Sweet Boy")
Facing a spirit
Shortly afterward, the Colinas de Oro War Relocation Center is shut down by order of the United States Supreme Court. Everyone is released. Asako and Henry return to Terminal Island only to find that their neighborhood has been raised and a fence placed around it declaring that the island is government property. Henry takes the job as a gardener and the two of them live in an encampment on Skid Row. Asako visits the bridge where her sister Yuko jumped from, committing suicide. She says that she should have done it sooner, that maybe if she had, then none of the terrible things that are happening now would have happened. She wonders if Yuko would be happy if she jumped off the bridge herself.
One day, Chester calls Henry, informing him that he and Luz have gotten married and that Luz is pregnant. Yuko is after the unborn child, hoping to claim it as her own. Asako and Henry travel to New Mexico to help Chester. Asako is pleased to be reunited with him, though Henry chastises him for letting her believe he was dead for many months.
When the initial plan to protect Luz fails, the group travels to a bunker on a New Mexico mountainside. There, Asako aids Luz's abuela Rocio Trujillo in delivering Luz's baby. Yuko possesses the child, a boy, and when the group realizes what has happened, she takes possession of Rocio instead, snatches the child, and starts to run off. Asako calls after her, telling her to stop and listen to her sister. She tells her that she was the one who wronged her most of all. She explains that Yuko was not originally promised to Hideo Furuya. She was, in fact promised to Henry Nakayama. Asako, hearing of Hideo's dishonorable nature, arranged things so that she would be promised to Henry instead and Yuko would be promised to Hideo. Yuko freaks out at this, shouting that all of her suffering is her fault. She strangles and beats her, then possesses Luz and runs off with the child. ("Come and Get Me")
She joins Henry in searching for Yuko after she runs off. They and Chester eventually discover that Yuko, possessing Luz, encountered a group of motorists and possessed their daughter, Esperanza, to take her back to a shack near the home of Luz's abuela. She is left to care for Luz, while Henry and Chester pursue Yuko into the woods. Luz, however, discovers a photo among Asako's possessions of Yuko when she was still pregnant with Chester (Taizo) and Jirou. This gives her an idea and she and Asako head into the woods as well.
There, Asako is shocked to discover that Yuko has killed her husband, Henry. She begs Yuko that if she wants someone to take her instead. She then pulls a knife and begins repeatedly stabbing at Yuko. Chester, however, stops her, telling her that it's pointless, that Yuko will always find a way. Luz, however, tells Chester of her plan - to use the curaranderismo magic to take Yuko back in time to the moment seen in the photo, when she was at peace. The magic works, and afterwards, Asako attends Henry's funeral. Five years later, she has her photo taken, holding a picture of Henry, at her son's new photo studio, H. Nakayama & Son Photo Studio. Her hair has grown somewhat scraggly and she still appears a bit haunted by her experience with Yuko. ("Into the Afterlife")