The nine adult movie stars told local media on Monday they could barely contain their excitement about the "Stop! AIDS" campaign event - which will be televised live - but asked, perhaps somewhat optimistically: please be gentle.
"I'm really looking forward to lots of people fondling my boobs," Rina Serina told the Tokyo Sports newspaper. "But I would be very happy if you would please be delicate."
The event, the 12th since its launch in 2003, will be broadcast on adult cable television, with punters donating to the anti-AIDS campaign in exchange for a feel.
It comes after sexist heckling of a Tokyo assemblywoman hit the headlines, highlighting old-fashioned views towards women that still permeate Japanese society.
"I never thought my boobs could contribute to society," added the ponytailed Serina, apparently unaware of any contradiction.
Fellow porn actress Iku Sakuragi had no qualms about being groped by hundreds of pairs of hands.
"It's for charity," said the 21-year-old. "Squeeze them, donate money -- let's be happy."
Lawmakers from Japanese Prime Minister Shinzo Abe's ruling party sparked a public outcry in June when they subjected Tokyo assemblywoman Ayaka Shiomura to sexist taunts, shouting "Why don't you get married?" at her during a debate on motherhood.
Japan has one of the lowest rates of female workforce participation in the developed world and a lack of childcare facilities, poor career support and deeply entrenched sexism are blamed for keeping women at home.
The 24-hour "squeeze-a-thon" begins at 8pm on Saturday (1100 GMT) and is backed by the Japan Foundation for AIDS Prevention.
