A video that shows two of the bonus features in the game.
First off is the collection system, where you need to collect scattered butterflies in the environment in order to unlock hidden bonus content. However you need to be careful as some butterflies are hidden and picking on bad actions could destroy them.
Second is Sarina's flute. At some point in the game, deep in the forest, Sarina and Toru come across a hidden capsule, in it is a mysterious instrument. Sarina discovers on playing the flute that it unleashes mystical powers. The player must learn a series of melodies to trigger these powers. However using these powers comes at a price.