Nao had a terrible childhood because her parents were alcoholics who didn't care about her at all. She fell in love with Mikiyasu Yasumori and married him. Together they had a son called Susumu. Mikiyasu's parents were loving people and Nao saw them as her own parents. She lead a very happy existence in the village of Sotoba.
Nao meets the Kirishiki's
While celebrating and lightening fireworks, the new Kirishiki family who moved into the Kanemasa mansion greeted them and Nao invited them into her house. After this event, Nao quickly fell ill in the days that followed. Dr. Ozaki determined that it was the same illness that killed Megumi and that he wasn't able to cure her. Mikiyasu was devastated when Nao died.
Nao is discovered by Toshio and Seishin
A few days after her passing, Nao rose as a vampire and began to take her family members out one by one, hoping they would join her in the life as an undead. She first killed her son Susumu, but he didn't rise. She then killed her husband Mikiyasu, but he also stayed dead. After this she targeted her mother-in-law Setsuko Yasumori. During this time, Toshio Ozaki had discovered the existence of vampires and decided to guard Setsuko in his clinic. When Setsuko began calling for Nao, Toshio and Seishin opened the curtains and discovered Nao, who was supposed to be dead. Nao couldn't enter the clinic because she lacked an invitation and so Nao left. Because Nao wasn't able to suck Setsuko's blood that night, Setsuko began to recover. The following night, Toshio once again guarded Setsuko. But Tatsumi decided to help Nao out and he
Megumi reminds Nao that none of her family members have risen
along with a group of other vampires invaded the clinic. Tatsumi cut off the power and got into the clinic, and jumped outside along with Setsuko, who had her blood sucked by Nao along with a group of other vampires. Because so many vampires sucked her blood, she died instantly. But Setsuko also didn't rise from the grave. Tokujirou Yasumori was the next person to be targeted by Nao. He also died and didn't come back as a vampire. Nao had killed her entire family and no one came back. She decided to kill her sister because they also invited the Kirishiki's into their home but they didn't get bitten by them. She felt it was unfair and thus killed her and her husband.
Nao's final moments in the pipeline
Nao was killed when the war between the humans and the risen broke out. She hid in the pipelines along with other vampires such as Ebuchi and Takatoshi Hirosawa.