With little fanfare, Nintendo has released the first DS game onto the Wii U in Japan. Brain Age, a brain-training game that sold over 19 million copies worldwide, is available for free download on the Wii U's Virtual Console until June 30th. It's a surprising move — president Satoru Iwata announced back in January that DS games would come to the service, but little has been heard of the initiative since. Nintendo released the first batch of Game Boy Advance titles for Virtual Console in April.

Brain Age is an unusual title that tells us little about how other DS games might work on the Wii U. The original release saw users holding the DS on its side, like a book, and using the touchscreen to write in answers to math problems, sudoku puzzles, and so on. On the Wii U GamePad, the two "screens" are arranged horizontally, which is convenient enough. But it's hard to imagine a similar setup for more traditional DS games, because the screen orientation would need to be flipped.

There's no word on a US release as yet, but next week's E3 conference in Los Angeles would be a likely occasion for Nintendo to announce further details.

Update: This story has been updated with information from Nintendo on Brain Age's release period.