About 100 MPs have offered prayers at the Yasukuni Shrine in Tokyo, a source of friction between Japan and neighbouring countries such as China and South Korea.
The day before Friday's visit, Japanese Prime Minister Shinzo Abe sent a ritual offering of a sacred tree branch to the 150-year-old war memorial, the first day of its four-day autumn festival.
The shrine honours the spirits of Japan's 2.46 million war dead, including 14 "class A" war criminals from World War II.
Seiichi Eto, the minister in charge of Okinawa and Northern Territories affairs, visited the shrine on Thursday, becoming the first minister to do so in two-and-a-half years.
Visits by Japanese political leaders to the Yasukuni Shrine invite the anger of neighbouring countries, especially China and South Korea, which consider the site to be glorifying Japan's wartime aggression.
China lodged "stern representations to the Japanese side for" Abe's offering and the minister's visit to the shrine, Chinese Foreign Ministry spokesperson Geng Shuang told a news conference on Thursday.
Yasukuni is "a spiritual tool and a symbol of the aggression war conducted by the Japanese militarists. The act of some Japanese politicians again shows the country's erroneous attitude towards its history of aggression," he said .
South Korea, which was under Japanese colonial rule between 1910 and 1945, also expressed its "deep regrets" over their actions.
Yasukuni "glorifies Japan's history of wars of invasion", Seoul's foreign ministry said in a statement, according to the Yonhap news agency.
Australian Associated Press