Sakura Kokumai, a Japanese American who will compete in karate at the Tokyo Olympics, has revealed on social media that a stranger recently targeted her in an anti-Asian rant at a park near Los Angeles.

Kokumai, a 28-year-old native of Hawaii, shared video clips from the April 2 encounter on her Instagram account. In one part of the posted video, a large man can be seen cursing at her, calling her a "loser" and insisting she "go home."

Photo taken on July 25, 2017, shows Sakura Kokumai. (Kyodo)

"I don't know which was worse, a stranger yelling and threatening to hurt me for no reason or people around me who witnessed everything and not doing a thing," Kokumai said in her post.

Although one bystander checked in with Kokumai and offered support near the end of the menacing encounter, the athlete said many others in the park failed to react or even smiled while passing by.

"Please take care of each other. Please look out for one another," she wrote. "This could have happened to anyone, if it wasn't me, someone could've gotten hurt."

A dramatic increase in anti-Asian hate crimes has been seen across the United States, with incidents frequently reported in major cities such as New York and Los Angeles.

The trend is believed to be partly linked to the spread of the novel coronavirus, which was initially detected in China in late 2019.