Principate
Saint Titanfall
I'm not so sure with the Vita TV doing nothing at its price and the regular 3DS selling just 30k this week, but who knows. Demand for cheap HW doesn't seem to be that big in Japan.
Vita TV isn't portable and the original 3DS is generally an inferior version of the XL (there I said it), a cheap price and a form factor close to the game boy may do well there. It's also doing very well in the rest of the world, so it wouldn't be surprising if there was demand in Japan.