While PS Vita's "Game Heaven" promotion failed to generate momentum for the ailing system in Japan, the Nintendo 3DS further entrenched itself in the handheld market with new third-party releases.Weekly hardware sales for Sony's new portable have been sinking for some time now, stuck at 10,000 units for the last two weeks -- a fraction of 3DS's weekly sales of around 70,000, and trailing behind the 16,000 sales from its seven-year-old predecessor, the PSP.Some have blamed the low sales on a lack of compelling software for PS Vita -- Sony held a "Game Heaven" online event for Japan last week that teased upcoming titles, but those announcements didn't appear to translate into more sales for the system.Only one PS Vita game made it into the top 20 software sales chart last week (tracking only retail sales, not digital copies), Zipper Interactive's newly released third-person shooter Unit 13. It's the only PS Vita title to chart in the last three weeks.Games for Nintendo 3DS, however, performed well, making up seven of the top ten best-selling games last week. Third-party titles, often cited as a weakness for Nintendo platforms, have enjoyed strong sales on the portable.Sega's new Hatsune Miku and Future Stars for 3DS was the second top-selling game after moving about 86,000 units. And Konami's Metal Gear Solid 3: Snake Eater 3D debuted with 38,000 copies, which is in-line with other recent re-releases for the franchise.Other third-party releases like Marvelous AQL's Harvest Moon: The Land of Origin, Capcom's Monster Hunter 3G, and Square Enix's Theatrhythm Final Fantasy continue to sell well alongside first-party titles like Super Mario 3D Land, Mario Kart 7, and Mario and Sonic at the London 2012 Olympic Games.Namco Bandai's PlayStation 3 game One Piece: Pirate Warriors was again the best-selling title last week with 90,000 copies sold, despite it reportedly moving 92 percent of its initial shipment and likely being supply-constrained.Capcom's Street Fighter X Tekken debuted last week, and the PS3 version was the third top-selling game with 58,000 copies, while the Xbox 360 version was the 14th with 8,000 units -- a little behind Marvel Vs. Capcom 3, but ahead of Ultimate Marvel Vs. Capcom 3.Full software and hardware sales charts for the March 5 to 11 period in Japan, provided by Media Create and translated by NeoGAF, are available here