Resembles a shark fin. It’s pale gold and gleams with a smooth surface that seems hard-word. it looks like a cross between plaster and plastic, bone fused in the shape of a boomerang the solid feel of power it contains augment ones natural abilities and enhance their combat skills. Because of its supernatural material, it's nearly unbreakable and is a very powerful weapon.

Hiraikotsu's name can be broken down into three components; Hi meaning 'flying', rai meaning 'come', and kotsu meaning 'bone'. The name itself has been interpreted many different way, but my personal favorite as well as the one sounding the best is 'The bone that flies back'

It can be used in many different ways. The leather bands towards either end allow her to grasp and handle easily. Other than using it as a boomerang, it can be swung and used as a melee weapon. Hiraikotsu is also big enough to be used as a shield when the need arises, and the nature of its materials makes it excellent for that purpose.