It appears that this float has an Undocumented Mark. This maker's mark has two distinct parts - a rectangle and a circle.
The upper part of the stamp has a rectangle containing two symbols. The first symbol is similar to WP #21. The second symbol in the box is a horizontal line that could be the Kanji for 'Ichi' 一.
The lower part of the stamp has a 'Tokui' 特 in a circle. I think this tokui most closely resembles WP #16.
This float measures 3 1/2 inches in diameter.
Found in Northern Japan.