In Castle Town, there is a large tent in the eastern part. Go inside and the ringmaster will ask you to play a star chasing game. Use the clawshot (hookshot) and collect all of the orbs in the cage within the time limit. Doing this challenge once gives you one upgrade.
The ringmaster will then have a second challenge. If you win this challenge within the time limit, the man will give you the Giant Quiver to hold up to 100 arrows.