As a human she was a large, ugly and obease woman. She wore tacky clothes and had her dark hair tied short. However in her youth she had been described as being thin and beautiful.
As a Devil Beast, she lost much of her weight, and sprouted black feathers from her chest, arms and head. She had large dark wings. Tail feathers sprung from her lower back and her feet resembled claws. She had wide eyes, a stubby beak lined with sharp teeth and a long tongue.
In her Devil beast form she could fly at fast speeds with her wings, and used her claws to cut and tear.
Before her partner had left her for another woman, she was described as a happy carefree girl, though one that had issues with her father. After the break up, Mrs. Kayama committed herself entirely to her daughter. Though instead of showing it through love and affection she became viscous. She pushed and fought for her daughters fame and popularity, her commitment weighed heavily on her, gaining a major amount of weight and loosing her beauty. She became a glutton and a bully. In spite of the sacrifices her mother had given for her, Nami was at times unable to decide if she loved her or hated her.
In the past she was described as being very happy with her partner however when he left her for a younger woman she became bitter and sour, and committed herself to ensure the fame of her daughter. Years later she had became heavily obese and bitter, in her drive for her daughters fame. Her disgusting nature had even caused her own daughter to begin hating her.
Shortly before one of Nami's performances, she had been talking to her manager Suganuma about Siren's and other ancient Greek myths when her mother comes running through yelling at the two for not being ready, much to Nami's annoyance.
Later the same night, she flew across the night sky in her avian form when she comes across a drunken man that reminded her of her father. She swoops down and claws his face leaving him screaming in pain. Then just after, she attacks a couple in a car and cause them to fly of a cliff, and die in the resulting crash.
Later after the attack had been reported Jun Fudo and Lan Asuka arm themselves with BB Enzyme Guns and go out in search of the rouge Devil Beast. As the two wait in stake out, Miss. Kayama spies a woman that had ignored Nami in a interview and swoops down for the kill. Lan and Jun hear her screams and follows the noise. After arriving the Devil Beast leaps at Lan however she is repelled when Lan fires several Enzyme bullets into her chest.
Jun arrives and picks Lan up, they tail the Devil Beast to her home. Inside Nami is shocked to see the creature come through her window, however it reverts into her mother and Nami runs to help her just as Lan and Jun arrive. Jun pleads for Nami to let them take away her mother to help her condition, however Nami instead screams at them and starts to transform herself, She attacks Lan, and starts to shred at her clothing. At the same time Jun transforms into Devil Lady and attacks Nami's mother who had begun to again, and breaks her neck. Nami sees this and attacks Jun, the two fly outside to continue their battle mid-air, meanwhile Lan regaining her senses sees Nami's mother sneaking up behind her, thinking fast Lan grabs a vase and smashes her on the head with it repeatedly till only a bloodied pulp was left.