Source Gamespot

Plumbing siblings make their comeback in their home country on May 25; game still on shedule for North American release on May 15.
Japan's Mainichi Shimbun and other media outlets report that Nintendo has fixed the Japanese release date for DS game New Super Mario Brothers. The highly-anticipated game is set to hit stores May 25 with a sticker price of 4,800 yen (about $40).

US gamers will get a head start when New Super Mario Bros. drops in North America on May 15. It's not clear why Nintendo has chosen to delay the launch in its home market, but it stands within reason that the company simply wants a few more days to build inventory. Demand for the title will no doubt be high, as the DS continues to be a popular seller.