Sega is launching a new something called Project 575. We assume it's a new game, since that's Sega's thing, but initial Japanese trailers leave a lot to imagination. They feature the silhouettes of girls in green and red, with background music that Siliconera identifies as work by Lamaze-P, a composer of Vocaloid music.
The red silhouette calls herself Masaoka Azuki, while the green one is Kobayashi Maccha, the site mentions. Project 575 has an official page and related social networking hubs. A YouTube commenter mentions the J-pop group, Perfume, has a song called "575" – this could be wishful thinking from a fan, but added to the Lamaze-P song, we're getting a distinct music-based vibe from Sega here.
See the second trailer, featuring just Masaoka Azuki (the red silhouette), below.