Japan’s famed “maid cafés” featuring coy young girls serving tea in frilly aprons and bonnets have been given a new twist – a café of unsmiling, grim-faced grannies reflecting a fast-greying nation.

Tokyo’s Ikebukuro district now boasts Café Rottenmeier, named after the disciplinary housekeeper in the hit 1970s anime series Heidi, Girl of the Alps, and has been drawing some 500 customers daily during weekends in November.

Patrons are greeted with a terse “welcome home” by an unsmiling Fraulein Rottenmeier lookalike before being scolded for slouching in chairs or for not removing their coats in the café’s warm, cosy environs.

There are 30 “Rottenmeiers” who work shifts, including students, office workers and retired real-life grannies, as part of the Festival Tokyo contemporary arts gathering being held until the end of November.

Although the “grannies” range from 24 to 77 years-old – with the younger matriarchs sporting heavy make-up to look old – the woman behind the concept says she is making a statement on societal pressures to stay young.

“Pressure on people to stay young is too heavy. It’s unnatural. I think people are exhausted under too much anti-ageing pressure,” 43 year-old artist Miwa Yanagi.

Especially in a country that is rapidly greying, with one of the world’s lowest birthrates of 1.3 children per woman taking a dwindling population even lower, helping deflate an already sagging economy.

The average age of Japan’s farmers, for example, is 66.

But Ms Yanagi also sees Japan’s elders as a cause for celebration.

“Japan is the world’s greatest nation of grannies,” she said, a reference to the nation’s average life expectancy of over 85 for women, the world’s highest.

Yet despite this, Japan “worships young women”, Ms Yanagi said. “It loves young women, as you can see in maid cafés or images of women in subculture. Why can’t there be a grannies’ café?”

The grannies, selected from some 50 applicants through an audition, were enjoying being old as much as clients seemed to be enjoying being disciplined said Naomi Akamatsu, a 42-year-old actress wearing fake wrinkles.

“Young boys and girls nowadays long to be scolded,” she said of the concept, which Ms Yanagi says demonstrates the need for strong elders in a nation of small, two-generation families.

Questions about the erosion of social bonds in Japan were raised earlier this year following a nationwide survey which found more than 230,000 registered centenarians were missing.

Japan launched the search after a string of grisly discoveries – including a mummified man in his bed and an old woman’s remains in a backpack – sparked alarm over the fate of many elderly.

The cases triggered a wave of soul-searching over elderly people living in isolation and public outrage at relatives of those missing who kept their deaths secret for decades in order to keep receiving their pension payments.

But while the café remains a lighthearted meditation on Japanese society, it is also a celebration of the Heidi legend.

Many of the customers were children when the Heidi anime first enchanted audiences on Japanese television in 1974.

The popular series, based on the 19th-century novel by Johanna Spyri, illustrates Heidi’s days in the Swiss Alps, with Fraulein Rottenmeier keeping a strict watch.

“I wanted to look at the world of Heidi I feel nostalgic about,” said Akiko Nagahama, 44, as she sipped tea at the café. “Rottenmeier left a very strong impression on me.”

Younger patrons such as Yui Tokunaga, 23, turn up just to see the older, hard-line contrast with Japan’s famous maid cafés, which usually feature young girls in skimpy outfits, bowing and kneeling as they stir drinks.

“I associate the image of maids as being cute, but here it’s fun to see them being not so,” she said.

Kayo Ishikawa, 66, a real grandmother of three who started acting after she retired, also enjoys being an unsmiling, dour Rottenmeier and remembers her daughters watching the anime.

“I think she is a woman who devoted herself to her job... I have the impression that she is a woman who earns money by herself and provides for herself,” Ishikawa said.

Yanagi, the artist, said it was great that “elderly women are ready to take on new challenges.”

And while she is too young to be a grandmother now, Ms Yanagi said she is ready to embrace the challenges of old age when they arrive.

“I’m looking forward to it,” she said.