A veteran porn star known only as Shimiken says he is one of just 70 male actors, with just a handful of them doing all the heavy lifting.
"Everyday I meet the same people and see the same names on scripts," he said on Twitter under his @shimiken username last month, adding the number was "lower than that of Bengal Tigers".
Quite why there aren't enough willing participants is a mystery to Shimiken: "This job is like an Aladdin's Cave, in many senses."
"In contrast, the number of porn actresses is as high as 10,000, with 4,000 movies released every month," Shimiken said. "We lack porn actors here."
The huge imbalance in the field stands in marked contrast to other areas of employment in Japan, where men outnumber women. Prime Minister Shinzo Abe has declared he wants 30 per cent of senior positions occupied by women by 2020.
The number of tigers in the world has fallen drastically from around 100,000 in the early 20th century to about 4,000 today, according to the international conservation body, WWF.
Most Bengal tigers live in India, where a little over 1,700 are found, according to another conservation group, the IUCN Global Species Programme.