WP #361 is a rare mark. The mark is comprised of the two symbols Ka か and Tsu つ.  Katsu かつ means win or victorious.

According to Walt Pich's 'Marks' book, there are only two known examples of this mark.  This float is the third float known example to exist in collections.

The other two are 10 inch floats.  One of these 10 inch floats has a blue seal button making it the only large blue dot with a maker's mark.  A true collector's prize.

This float is 12 inches in diameter making it the only known 12 inch float with mark WP #361.

This float has excellent provenance having been found in Japan by Kala & Aragon Ellwanger in 2020.