Blue Dragon is Microsoft's attempt to truly break into the Japanese console market. The Blue Dragon launch can be billed the REAL Xbox 360 launch day in Japan; at least, Microsoft hopes it is.
According to a confusing machine translation from GameSpot China, the Xbox 360 sold either 27,000 or 70,000 units to accommodate the release of Blue Dragon. If 70,000 is the correct number, an additional 43,000 units of Blue Dragon sold (which is the bulk of the Japanese owners who previously purchased an Xbox 360). In either case, this is certainly a nice boost for Microsoft.
If the 70,000 is the correct version of the translation, it would certainly be odd to see the Xbox 360 sitting at a solid #3 on Japan's weekly sales chart. Microsoft hopes to sell 200,000 copies of Blue Dragon in Japan, which means Microsoft hopes to have around 200,000 Xbox 360 units in Japanese households. While not impressive from the standpoint of, say, the DS -- Nintendo sells that many in two weeks -- Microsoft should enjoy the sales boost and the publicity that goes along with it.