Zen

While fairies are the only species in the over world that could transform naturally, Harpies are the only species in the Above World that can transform naturally. Because they are a holy species, known for being protectors and messengers for angels, they were given the ability to transform for when they go down to the Overworld. However they can't transform COMPLETELY, their bird like legs cannot transform into human legs, leaving them to constantly wear pants instead.

Zen wears roll up pants to allow him to transform in between with ease.