Mark #39 is 'Mata Masa'.  The symbol on top of the stamp is 'Mata' 又.  The symbol on the bottom is 'Masa' 正.

According to Walt Pich there were two examples of this mark known to the collection community at the time his 'Marks' book was published in 2009.  One found in Alaska and another in Japan.

This could be the third known example of mark WP #39 Mata Masa. These are the only three that I'm aware of but there may be more of them out there.

I purchased this float in Japan in May of 2023.