Top Japanese TV hostess talks in N.Y.

''The Barbara Walters of Japan'' is now also the bestselling author in Japan. Not only is Tetsuko Kuroyanagi as famous as her American counterpart for her daily news and talk shows (she was voted Japan's most popular TV personality for six years running), but she is now also the author of the bestselling book in Japanese publishing history.

''Totto-Chan, the Little Girl in the Window,''just published here in English is a charming series of childhood recollections about Miss Kuroyanagi's early years in a unique school in Tokyo during World War II. It has already sold more than 6 million copies in Japan.

Visting the United States to promote the book, Miss Kuroyanagi has appeared on the ''Tonight'' show with Johnny Carson, where she proved to be an enormous success by simply being her modest self. Joan Rivers, another guest, even offered to find the Oriental beauty a husband.

Now, at lunch at the nouvelle cuisine restaurant of the Grand Harley Hotel in New York City, she is pleased to find red snapper sushi on the menu. ''So much Japanese food in New York,'' she murmers as she orders it. Dressed in traditional Japanese robes, her black hair, powdered white complexion, and delicate Oriental features draw attention even in a city that has become used to unusual visitors. The classic Eastern delicacy of her beauty attracts the eyes of all the other diners, some of whom turn and stare impolitely. Beneath the Kabuki-masklike makeup the interviewer could just about detect the pale pink of a blush.

A story has been circulating about Miss Kuroyanagi which seems to be apocryphal: When she was a little girl, her mother supposedly took her to the principal of a new school for an interview, and when asked to talk she spoke for four hours without a break.

''It is true,'' she insists. ''And I have not changed all these years. I am still talking.'' She giggles pleasantly.

''Children need this kind of treatment. I think all young people should be encouraged to develop their character before they become adults.I have been working for blind and disabled children for 20 years. Now, with the royalties from my book, I'm starting the Japanese Theater for the Deaf.

''The book is to try to break the pattern of pressure in the Japanese educational system. Children are forced to study from kindergarten through college to get into a good company.''

Many parents in Japan instill the feeling in their youngsters that, if they don't attend the very best schools from kindergarten on, they are doomed to be locked out of top jobs with the top Japanese corporations. It's a bit like the drive to attend Ivy League schools among some segments of the population in the US. Only it starts much earlier in Japan.