Final Fantasy Crystal Chronicles: Chiisana Ousama to Yakusoku no Kuni
This game is titled Final Fantasy Crystal Chronicles: My Life As A King in North America and Final Fantasy Crystal Chronicles: Chiisana Ousama to Yakusoku no Kuni in Japan.
Successfully complete the game. You can now start a "New Game +" under the Hard or Very Hard difficulty setting. Although the dungeons will be more difficult and you will lose all your buildings and research, you will still have the characters, items and medals earned during your original session.
Strategy guides from GameFAQs