Capcom pushed back the Japanese release of Monster Hunter 4 from March to TBA summer 2013. At the time, the company said it made the decision in order to improve the game’s quality. But Japanese magazine Game Lab offers a different reason: Monster Hunter 4 is also in the works for the PS Vita.
For what it’s worth, Game Lab’s rumors tend to be hit or miss. A considerable amount of its speculation never resulted in anything, but it was one of the first sources claiming that God Eater 2 would be made for the PS Vita.