The South Korean government has expressed deep regret over the Japanese Prime Minister's ritual offering to a controversial war shrine on a key anniversary for both sides.
Japan's Fumio Kishida sent the offering to the Yasukuni Shrine on Monday.
His two Cabinet ministers also visited the shrine, which is seen as a symbol of Japan's past militarism.
This came just hours after President Yoon Suk-yeol called for an improvement of frayed ties during a ceremony to mark Korea's independence from Japan's colonial rule.
August 15 is the anniversary of Japan's surrender in World War Two.
It is celebrated in Korea as Liberation Day.
South Korea urged Japanese leaders to face up to history and demonstrate humble introspection and genuine self-reflection.
The Yasukuni Shrine in Tokyo honors 2.5 million Japanese war dead, including 14 Class-A war criminals.