Thought Catwoman was only a fictional character from the Batman franchise? Well, maybe not anymore.

A 20-year-old girl from Oslo in Norway believes she is a cat trapped inside a human body.

Appearing in a news broadcast posted to the NRK P3 Cerdens Rikeste Land YouTube channel, the girl named "Nano" asserted that she has "been a cat all [her] life."

The Norwegian girl, who wears fake cat ears and a tail, also said she was "born in the wrong species." She said she came to this realisation some four years ago.

"I realised I was a cat when I was 16 when doctors and psychologists found out what was 'the thing' with me. Under my birth there was a genetic defect," Nano said, as quoted by Christian News.

Asked if she believes she has been a feline since birth, the girl answered, "Yes. I am born like this... Born in the wrong species. ... It's obvious I'm a cat when I start purring and meowing and walking around on four legs and stuff like that."

True enough, Nano crawls on her hands and knees to move around. She also has the habit of scratching doors.

At one point during the interview, the girl also hissed and jumped back when she saw a dog, just like what a cat will do. Nano also said because of her feline instinct, she "automatically reacts by hissing."

More bizarrely, the girl also claims she prefers to sleep in the sink and on window sills than on her bed, and that she likes to chase mice.

"I have been running a lot after animals that can be seen in the shadows," she said. "I have tried, but have never managed to catch [a mouse]."

Although her psychologist said she will eventually outgrow her belief that she is a cat, Nano is convinced that she will be a feline all her life.

"It is exhausting, but you get used to living with cat acts and cat instincts," she further said. "My psychologist told me I can grow out of it, but I doubt it. I think I will be cat all my life."