Shinjiro Koizumi, Japan's agriculture minister and a contender in the ruling Liberal Democratic Party's leadership race in 2024, arrived at the Yasukuni Shrine in Tokyo early on Friday.
Among the 2.5 million war dead commemorated at the shrine are 14 wartime leaders convicted of the most serious war crimes, along with over 1000 others found guilty by Allied tribunals after Japan's 1945 defeat.
China and South Korea have criticised past visits by senior Japanese officials that they say gloss over Tokyo's wartime actions and damage diplomatic ties.
"It is important never to forget to show respect to those who gave their lives for their country, regardless of which nation it is. I believe this is a very important principle," Koizumi told reporters.
Prime Minister Shigeru Ishiba attended a separate war memorial event in Tokyo along with Emperor Naruhito.
"August 15 is a day to mourn the war dead and commemorate peace. The government will continue to express gratitude to the war dead and their families," government spokesman Yoshimasa Hayashi said at a regular media briefing.
No sitting Japanese prime minister has visited the Yasukuni Shrine since Shinzo Abe in December 2013, drawing an expression of disappointment from then-US president Barack Obama.
The last premier to visit on the anniversary of Japan's surrender was Koizumi's father, Junichiro Koizumi, in 2006.
Former economic security ministers Sanae Takaichi and Takayuki Kobayashi also went to the shrine, local media reported.
Both ran in 2024's LDP leadership election.
Ishiba on Friday sent an offering to the shrine, according to local media.
One he made in October provoked criticism from both South Korea, a Japanese colony for 35 years, and China, whose territories were occupied by Japanese forces in World War II.
Chinese Foreign Minister Wang Yi on Friday urged Japan to confront its history of wartime aggression and called on the country to make "the right choice".
Wang stated that certain factions in Japan continued to attempt to "glorify" and deny its history of war aggression.
The anniversary comes before an expected meeting with South Korean President Lee Jae-myung who will visit Japan on Aug 23-24 to discuss regional security and trilateral ties with the US.
On August 15, his country celebrates its liberation from Japanese colonial rule.
While relations between Tokyo and Seoul have often been strained, the two countries are deepening security cooperation to counter China's growing influence and the threat posed to both by nuclear-armed North Korea.
As many 88 national and local MPs from Japan's far-right Sanseito Party also visited Yasukuni, local media reported.
In July's upper house election, it won 13 new seats, drawing support away from Ishiba's LDP.
