I really do recommend buying it. A lot of good artists on DeviantART use and it only costs around 60 dollars (5250Y to be exact), which I think is a great deal compared to other software on the market and it's the program I plan on purchasing soon.
And Ping is totally right, unlike the Americans, the Japanese have a firm hold on their software xD
You do need paypal but the good news about that is they send you the code by email as soon as they confirm your order, so you don't have to wait for the disk from Japan and can probably start using it within the day.
Here's the link to where you can order it in English... Hopefully I'm not breaking any rules by posting it (I don't think I am) o3o; *whistles* just helping out a friend here.... *quietly shoves link into Skunker's hands*
http://www.systemax.jp/en/sai/