After a decade of peeling off for X-rated movies, a Japanese porn actress famous for being the country's oldest has called it quits, at the ripe old age of 80. Maori Tezuka, a former opera singer who made her debut in Japan's flourishing "silver porn" industry at a sprightly 71, blamed her decision partly on a lack of red-blooded Lotharios able to keep up with her. Geronto-porn is not for the faint-hearted but is big business in Japan, where around 34 million people or a quarter of the population, are over 65. Japan's porn industry rakes in about USD20 billion a year, with movies featuring rambunctious geriatrics accounting for around a quarter of that market, industry insiders say. In recent years sales have soared as more of the country's perky seniors celebrate their mojo. The genre took off, thanks largely to the exploits of Shigeo Tokuda, an 82-year-old actor who has appeared in hundreds of blue movies.