Very Small Vintage Childs Motorcycle Helmet

This is the smallest functional motorcycle helmet I have ever seen. It is a childs size small, who would make that?
There are no markings other than a z 90.1 tag on the inside.

It looks to me to be early 70's Japanese construction. The shell is fiberglass and the trim is nice wide rubber. It is well made.

I have included an image of the hat along side an adult size large helmet for comparison.