TOKYO, March 22 (Reuters) - Japanese firms have agreed to raise pay by 5.25% this year, the biggest amount and ratio under comparable data available since 2013, the country's largest union group Rengo confirmed on Friday.

Prime Minister Fumio Kishida has said the government is counting on such wage hikes to trickle down to smaller and medium-sized firms, which account for a whopping 99.7% of all enterprises and about 70% of Japan's workforce, but many lack the pricing power to pass higher costs to customers.

"We will examine how broad the trend of wage hikes is spreading at a meeting on April 4," Akira Nidaira, a senior Rengo official told a news conference. (Reporting by Tetsushi Kajimoto; Editing by Himani Sarkar)