The 3DS has been dominating the PlayStation Vita ever since the holidays, and it doesn't seem that Nintendo will be letting up. According to Media Create Sales for the week of January 15 to January 22, the PS Vita is still having trouble establishing a base in Japan.
Overall, the holiday rush has been slowly dying off, and all console sales have dropped about 20-30% since the week before. Using rounded numbers, the 3DS alone has dropped from 100,000 units sold to 80,000, but that's still five times the sales figures of the PS Vita which slipped from 18,000 units to 15,000 units. In fact, that's still fewer than sales of the regular PSP, which sold 17,000 units during the week.
However, Sony should be happier with their performance with stand-up consoles. Though Wii titles still remain successful in Japan, with 6 Wii titles within the bottom half of the Top 20, only 10,000 Wiis were sold this week, compared to 21,000 PS3 units sold. As the Wii U remains in development, we can only suspect that the Wii will slowly be overshadowed in the near future.