Nayuta/History

Control Devil arc
After the defeat of the previous incarnation of the Control Devil, Nayuta incarnated in China as the new one. Kishibe found her and brought her to Japan.

During the meeting between Kishibe and Denji, Nayuta approached them by hugging one of Makima's dogs. Kishibe introduced her to Denji while she was biting one of Denji's fingers. Denji remembers this bite from the time Makima bit one of his own, immediately making the connection between the two. Kishibe goes on to say that Makima is effectively gone, and this new Control Devil must not be allowed to go down a similar path, thus leaving Nayuta in Denji's care rather than the Public Safety's.

Justice Devil arc
Nayuta was seen sleeping with Denji and their dogs while Yuko was beheaded by a figure resembling Chainsaw Man. Later, when Denji and Asa Mitaka are trapped in the Tanashi Aquarium by Fami, Denji reveals that, despite her young age, Nayuta is smart enough to go to college, and he is paying her tuition.

Current Ar c
Nayuta goes out for a walk with the dogs. When she returns home, she finds Denji and Yoru kissing. She calls Yoru a thief and points at her, linking a chain through Yoru's skull. With the chain, Nayuta has Yoru barking like a dog, to her amusement. Denji tells Nayuta to turn her back immediately, which she agrees to do as soon as she is fed. While she eats, she asks Denji if he is sure he wants to turn "Asa" back, adding that every woman he meets tries to kill him. Denji replies that it is just a feeling, and she complies, but on two conditions: allow her to eat ice cream every day and not make friends with Asa anymore. When asked why, Nayuta explains that "Asa" has a bad scent and proceeds to say she will alter her memories to make her believe that Denji stood her up. Denji is conflicted but decides to put Nayuta first, and she replies with a peace sign.