TOKYO—Japanese 13-year-old Momiji Nishiya clinched the Olympic title in the women’s street skateboarding competition on Monday, shedding tears of happiness after nailing her final trick and becoming the country’s youngest-ever gold medal winner. Nishiya came out on top of an unusually young field of competitors, with all three medalists in their teens. Brazilian silver medalist Rayssa Leal is also 13, while bronze medalist Funa Nakayama, also from Japan, is 16. Her victory brought a skateboarding double for Japan after Yuto Horigome won gold in the men’s street event on Sunday, claiming the first gold medal for the sport in Olympic history. “I welled up in tears because I was beyond happy,” Nishiya said, describing the moment when she realized she had won gold. Though Nishiya said she was “stressed out” after initially stumbling and missing key landings on her first two tricks, she landed her final three, earning 4.66 on …