Pairs of lion statues guard the entrances of temples and shrines across Japan. The carvers would not have seen real lions and used designs from Chinese art where the animals have curly manes like Pekingese dogs.
The ‘Chinese lion’ on the right of an entrance is called a karashishi, and has an open mouth to scare demons away. Often karashishi hold a ball in their feet, representing a wish-granting jewel.
In this lion’s mouth of this carving is an even smaller ball, which appears and disappears when the netsuke is moved.