This is a ball used by girls to play handball called Temari, or made as an ornamental object.
 
Itomari (Treads ball) is a type of ball made by using cotton thread wrapped around a rolled cotton core, and has been developed as a plaything for girls since the Edo period.
 
This is a set of two balls on a single piece of thread.
 
Measures: 7cm (2.7in)