Japan rode a strong first-half performance to a 34-21 victory over Fiji, beating the Pacific islanders for only the fourth time and ensuring their World Cup preparations were progressing steadily.
In their opening match of the Pacific Nations Cup, in the northern city of Kamaishi, a full-strength Japan led 29-14 at half time courtesy of tries by wingers Kenki Fukuoka and Kotaro Matsushima, centre Timothy Lafaele and flanker Kazuki Himeno.
Centre Leveni Botia and hooker Sam Matavesi replied for the Fijians before the break, but 15 points proved too big a deficit for the Pacific Nations Cup champions to overhaul in the second half.
The impressive Matsushima added another try in the 54th minute to stretch Japan's lead, but Fiji attacked with more urgency against the tiring hosts, wresting back both possession and territory.
Fiji hooker Matavesi again scored a converted try on the hour mark as the visitors used their superior forward strength to dominate Japan in the maul.
But Fiji's comeback attempt sputtered as their feared attack became more disjointed in the sweltering heat of Iwate's Kamaishi Recovery Memorial Stadium, allowing Japan a win over an opponent two places above them in the world rankings.
Japan face Tonga in the second round of the Pacific Nations Cup on August 3.
The tournament is a crucial buildup for the Pacific nations ahead of the World Cup in Japan in two months time, with the United States, Canada and Samoa also taking part.