Know that you'll be forwarding time alot with the Song of Double Time, but it (obviously) speeds up the waiting process. Start by being on the 1st day and forwarding time to 10am and then going to the Mayor's Office. Go to the right room and talk to the woman in orange. Say "Yes" and you'll get Kafei's Mask. Go to the Stock Pot Inn at 3pm and show it to Anju. Go outside and forward time to 11pm.