Japan enacted the Act on Punishment of Activities Relating to Child Prostitution and Child Pornography and for the Protection of Children in 1999. While this law explicitly outlawed explicit depictions of minors, it contained regulatory gray areas regarding "non-explicit" gravure modeling (such as swimsuits or fitness attire). This exception allowed the mid-2000s junior idol market—the exact era when Anna Oonishi was active—to continue operating commercially. 2. The 2014 Legal Reform
If you are interested in current Japanese stars named Anna, you might want to check out Anna Tanaka