Nishiya, from Osaka, topped a youthful podium after 13-year-old Rayssa Leal took silver and Nakayam Funa, 16, won bronze.
With an average age of 14 years and 191 days, it is the youngest individual podium in the history of the Olympics. Leal would have become the youngest individual Olympic champion had she won but Nishiya bettered her score of 14.63 after a strong finish to take gold with 15.26.
The youngest-ever Olympian is Marjorie Gestring, who won the springboard title at the 1936 Berlin Games at the age of 13 years and 267 days; just 63 days younger than Nishiya.
But both athletes could have their records toppled if Great Britain’s Sky Brown can win gold in the women’s park skateboarding on Wednesday, August 4.
At just 13 years and 28 days, Brown will make her own piece of history by becoming Britain’s youngest-ever Olympian, but if she wins gold she will not only usurp Nishiya’s skateboarding record, but also Gestring's overall record.
And with Japan’s Kokona Hiraki competing in the same event at the age of 12 years and 343 days, even more records could be smashed if the Hokkaido native can medal.
Skateboarding was one of four brand new sports added to the Tokyo Games along with sport-climbing, surfing, and karate, with softball and baseball making a comeback as well.