PS Vita hardware sales sank to 8,250 units in Japan last week -- a record low for the struggling handheld that's had no blockbuster game releases to help lift it out of this rut.

Sony's new portable has had little success gaining upward momentum in recent months. Its sales are tracking far behind its main rival, Nintendo 3DS (sold 63,796 units last week), which is so far outselling PS Vita six-to-one in Japan this year.

Many have blamed PS Vita's poor sales on a lack of compelling software, as Sony and third-party publishers haven't released any big-seller in Japan for months. It won't receive any major titles until mid-to-late June with Persona 4: The Golden and Metal Gear Solid HD Edition.

And though handheld games for DS, 3DS, and PSP dominate Japan's top 20 software sales chart for retail (taking 15 spots), the list lacks a single PS Vita title -- the chart does not take into account digital sales for PS Vita games via PlayStation Network.

Namco Bandai's 2nd Super Robot Wars Z for PSP was the biggest-selling game for the second week in a row after moving 34,403 copies. It's followed by Square Enix's Kingdom Hearts 3D for 3DS, which dropped off fast and sold 20,977 copies last week after debuting three weeks ago.

Several other Nintendo 3DS games continue to sell well, including Super Mario 3D Land (18,119 copies), Kid Icarus: Uprising (15,228 copies), Mario Kart 7 (12,212 copies), and Capcom's Monster Hunter 3G (15,074 copies).

Two new PSP games from Idea Factory debuted in the top 20 list last week, Atelier Elkrone: Dear for Otomate (8,012 copies) and Armen Noir Portable (3,254 copies). PSP hardware sold 13,166 units -- the seven-year-old portable has so far outsold PS Vita in 2012.

Full software and hardware sales charts for the April 9 to 15 period in Japan, provided by Media Create and translated on the NeoGAF forums, are available here.