The moon-faced creation that adorns everything from pencil cases to pyjamas the world over is, in fact, human.
"Hello Kitty is a cheerful and happy little girl with a heart of gold," brand owner Sanrio says on its website.
The shocking revelation came to light when a Hawaii-based academic specialising in the epitome of "kawaii" ("cute" in Japanese) asked Sanrio to fact-check captions for an exhibition she was curating to mark the 40th anniversary of Hello Kitty
Christine Yano, an anthropologist from the University of Hawaii, told the Los Angeles Times that she "was corrected -- very firmly" by Sanrio that Kitty was not a cat.
"That's one correction Sanrio made for my script for the show," the paper quoted her as saying.
"Hello Kitty is not a cat. She's a cartoon character. She is a little girl. She is a friend. But she is not a cat. She's never depicted on all fours. She walks and sits like a two-legged creature."
And indeed, an AFP enquiry as to the status -- feline or otherwise -- of one of Japan's most famous exports confirmed her non-cat identity.
"It is a 100-percent personified character," a Sanrio spokesman told AFP in Tokyo. "The design takes the motif of a cat, but there is no element of a cat in Hello Kitty's setting."
- Agog at the news -
Her real name is Kitty White, he explained, and she was born in southern England on Nov 1, 1974. She is a Scorpio and blood type A.
She has a twin sister, Minny White, and lives in an unnamed suburb of London with father George and mother Mary, according to her profile on the web.
Despite her whiskers and pointy ears, just like the rest of her family, Kitty has her own pet -- a "real" cat named Charmmy Kitty.
Her life story has always been there, the spokesman said, adding the personification is meant to make her fans feel closer to the character "as a friend".
Web users were agog at the news.
"Hello Kitty is not actually a cat. MIND BLOWN", tweeted @killedbydying
"'Sanrio confirms that Hello Kitty is NOT a cat.' One of the many reasons why I have trust issues", wrote @eisakuivan
"So Hello Kitty isn't a cat? Everything I know is a lie," said @nymbc
Asked about the worldwide reaction to the shock revelation that Hello Kitty is not a cat, the Sanrio spokesman offered: "I don't think anyone in Japan found it surprising."
"There is an explanation we have made the whole time, and I think that's how people have understood it."
A straw poll of Japanese people within the AFP Tokyo bureau found that not to be the case, however.
The Sanrio spokesman explained that Kitty and her family were given no specific nationality but were designed to be living in Britain, because many girls in Japan had strong admiration for the Western lifestyle in the 1970s.
Ever since the mouthless white character first appeared in 1974 on a coin purse in Japan, she has graced tens of thousands of products, from handbags to aircraft, in some 130 countries.
But just remember: she's not a cat.