No necessarily.
Most of the actresses are surely not virgins when they enter JAV. But as the number of actresses popping up each month isn't that small there are maybe one or two who are really virgins. But I guess they would never tell it the production company or the studio. It's like you want to get a job and have to admit that you have no knowledge about it at all and never worked in that field. Would the company employ you? I guess not.That "virgin" is only some kind of label for the movie so it sells better. It's the same fake like most of these Chinkan scenes in the bus or train. They're also not shoot in a regular bus or train. And all the people there are hired. Or many of these amateur movies. You often see well known actresses in it. That they don't list their names doesn't automatically mean they are amateurs. And so on and so on.