After clearing main story of The Legend of Zelda: Skyward Sword HD, new features can be accessed by starting a new game. Below are all post-game unlockables and useful information on each of them.
After clearing the main story, Hero Mode is unlocked. This allows you to begin a new game with various changes and restrictions applied to make the game more challenging. In Hero Mode, enemies deal twice as much damage, hearts cannot be obtained from plants and pots (apart from holding the Heart Medal), and other differences.
No Rewards for Clearing Hero Mode
There are no rewards for beating the game on Hero Mode other than experiencing the main story on its hardest “difficulty”.
Demise Boss Rush Battle
The Demise boss fight in Thunder Dragon’s Lightning Round (Boss Rush) in Lanayru Gorge is unlocked in Hero Mode. Note that you still need to progress through the main story to access the boss rush challenge.
Beating all 12 challenges in the Lightning Round rewards you with 9900 Rupees. You will need the Tycoon Wallet (obtained after delivering 80 Gratitude Crystals to Batreaux), including all wallet expansions, to carry this massive amount of Rupees so be sure to get it before clearing the Demise boss rush fight.