This 5 inch float is stamped with the WP #356 mark. The mark consists of the hiragana character for the letter 'no' の under a roof.
It also has a wonderful old sisal net that really adds to the visual appeal.
Mark WP #356 is typically found on 3 1/2 floats so this float is pretty rare. It's one of three 5 inch WP #356 marks sold by eBay vendor Ogkyo in 2018.
Found on Hokkaido Island, Japan.