From Porniki

Asian porn covers any porn either produced in Asian countries, or which features asian models.

This breaks down into two groups

1. Americanized or Westernized asian porn. This usually involves girl that appear asian on the outside, but are usually fluent in english. Often part of interracial setups.
2. Asian market porn. This is often much more interesting material featuring girls that are rarely seen in North America. Japan in particular has a very large and vibrant porn industry.

It should be noted that man movies from asian markets contain material that might be considered offensive, obscene, or even illegal in the United States or Canada. The relationships in the Japanese market between men and women are somewhat different than in other places, and many of the porn movies rely on subject matter of force or unwanted sex encounters, public sex, extreme fetish including things like urination and scat, and other subjects that might not be suitable for everyone. The cultural differences between NA and Japan make these things acceptable to them but not always acceptable in the US or Canada. They are also more than willing to explore sexual fantasies regarding schoolgirls, and it is not unusual to find vending machines that sell used panties (along with a picture of the girl who wore them).

Until very recently, all movies from Japan had the genital areas blurred by mosiac, as required by both law and tradition. Recently more non-mosiac movies have come out, which suggests that this might be a fading tradition.