If you refer to my post about Harajuku fashion you will see that Decora is a type of Harajuku. It is a more ‘decorated' version. The decorations are generally cute, colorful, themed accessories.
Decora is all about layers; layers of accessories and layers of clothing.
These styles have decreased in popularity over recent years and Fairy Kei has replaced it as well as Lolita – which I write about here. The fashion has spread to the West though where it thrives anew!