Skateboarding has a new king, and Japan has another fine reason to cheer these troubled Olympics. Yuto Horigome, 22, who served notice that he was a threat by winning at the Street Skateboarding World Championships in June, earned the sport’s first Olympic gold medal in the sweaty heat on Sunday at Tokyo’s Ariake Urban Park. When skating during his runs, Horigome almost looks effortless: Was he really trying?