pachinko parlours aren't easy to get into as a foreigner. As far as I know, many of them really are run by yakuza, and they don't really want foreigners in their parlors because they're far less likely to play on the machines for an extended length of time. A few times we walked past the parlours and I would see parents in there with their kids lying on the floor with a blanket over them, sleeping, while the parents just played and played and played. It was really disheartening, I felt so sorry for the kids.
Also, unless you already have an understanding of the game, it wouldn't be very easy to get started. From what I heard, the way they get around the whole gambling thing is you have to buy buckets of the silver round balls, and then you take those balls and use them to play the machines. But that's if they'll sell you the balls, and like I said previously, the ones who run the system want players who will stay there for a long time so they can get the most money out of them.
I tried to go in myself in 2008 so I could look at the Gackt Gladiator machine, but I got so many evils from the staff that I didn't even try to ask how to play. It was obvious they didn't want me there at all.