This 5 inch float is stamped with 'Naka 中 under a Roof' mark.  The Naka 中 symbol is at 90 degree angle to the roof mark rather than vertical to the roof mark as depicted for WP #44 in Walt Pich's Marks book.  So, it's unclear if this is a new undocumented mark or not.

This looks like an older float and is nicely netted for displaying.

Found on Hokkaido Island, Japan.