Lady Gaga, a U.S. diva working to help people infected with HIV, gave a special concert in Tokyo on Tuesday and urged people in Japan to be more open to discussing the issue.

Lady Gaga, together with dancers, performed in front of a couple of hundred fans and celebrities at what used to be a printing plant along Tokyo Bay.

During the 20-minute show she also played a white custom piano, which is scheduled to be auctioned in New York at the end of April to raise funds to help people with HIV.

"In Japan, women and men do not want to talk about AIDS or HIV. It's really uncommon," she said in an interview earlier in the day. "We're here now to put it on the table, not under the table."

Lady Gaga, who has been on her Monster Ball tour in Japan since last week, has become a spokeswoman for Mac Cosmetics' campaign to provide funds generated through lipstick sales to organizations helping people affected by the virus.

"I sing about sex, I dress sexy . . . but I want my fans to respect themselves," she said, warning against unprotected sex.

The cosmetic company's president, John Demsey, said the firm chose Lady Gaga as a spokesperson for its Viva Glam campaign because she is a "leader for young people and she is not afraid" to talk about uncomfortable matters.

The number of people in Japan newly diagnosed with HIV/AIDS came to 1,428 last year, down 8 percent from 2008. Although the figure marked the first year-on-year decline in seven years, health ministry officials noted that it also came in tandem with a 15 percent drop in the number of tests for HIV/AIDS.