Hey,I contacted the developer and asked if they where working on a harvest moon game for the vita and they replied saying,
You never know what the future may hold,but we do not have any plans on announcing a vita game at the moment.
I hope there will be a port of ps2 " harvest moon a wonderful life "or a whole new game that has the same feel as "a wonderful life"
This is there official facebook page I contacted them by:
I think if more people ask them and send them messages on development of there games for vita that could encourage them to make games for it more or announce something