When Naomi Osaka walks onto the court at the Billie Jean King National Tennis Center in Queens, N.Y., this week, she will be covered in bows.

One large bow is pinned like a pillowy prize to the back of her bomber jacket. Underneath her jacket, on the back of her competition dress, a smaller shiny bow rests on four tiers of ruffles. Two tiny bows are stuck to the backs of her shoes.

“Be very honest,” the designer Yoon Ahn said she told Ms. Osaka when they were conceptualizing the look. “There are no wrong ideas. What are you into right now?”

Ms. Osaka responded with Japanese subculture references, said Ms. Ahn, who co-founded the Tokyo label Ambush in 2008 and began collaborating with Nike in 2018. (On Aug. 27, Ms. Ahn will release an eight-piece collection of vintage tennis-inspired clothing for Nike Women.)

“She sent me a few looks of this ‘Lolita’ goth thing she was really vibing at that moment,” Ms. Ahn said. “They go out and wear pink, frills, bows, lace. It’s about really owning the cutesy-ness and the girly-hood.”

Two versions of Ms. Osaka’s U.S. Open look were made: one in black, for evening matches, and another in green, for daytime competition. (Nike also made a version for her 1-year-old daughter, Shai, who “might” watch her mother play, Ms. Osaka said.)