Do women wear underwear underneath their swimsuit in Japan?

Do women wear underwear underneath their swimsuit in Japan ?

• I've heard from my friend who travels to Japan a lot that there is a special underwear just for swimsuit. It this true ? If so how often do women in Japan wear those underwear ? Is it common for them ?

• Answer:

  Apparently, they do. It's a special kind of underwear that presses the stomach down so that you look thinner. It comes with some swimsuits, but not all. It doesn't work with bikinis. In swimsuits for older women, it comes with the underwear. People who wear one piece swimsuits usually wear this underwear. Wow, this is new to me, too. -.-"