That’s the first letter of YONEX!

YONEX was originally called Yoneyama, abbreviated as YY. As for the name change, it was because of the strong impact of the KENNEX 787 racket that we had to "learn from it" The second half of Taiwan's KENNEX was rewritten as YONEX.

As for the meaning, I feel that the Y is an abstract shape of a badminton.