Japanese Prime Minister Sanae Takaichi played two K-pop songs during a post-summit drumming session with South Korean President Lee Jae Myung.
Mr Lee joked that he felt "a little awkward" in front of Ms Takaichi, a former heavy metal band member.
The two leaders, dressed in matching blue sports tops personalised with their names, posted images of themselves on X jamming after they met in Mr Takaichi's home region of Nara.
During talks they agreed to strengthen cooperation on economic security and regional and global issues, according to South Korea's presidential office.
Ms Takaichi stressed the Asian neighbours "should cooperate to ensure regional stability".
"Following the summit I played drums with President Lee Jae Myung," Ms Takaichi, she said in her social media post.
"When we met at APEC (Asia-Pacific Economic Cooperation forum) last year, he said it was his dream to play the drums, so we prepared a surprise," she said.
韓国の李在明大統領と首脳会談を行いました。
— 高市早苗 (@takaichi_sanae) January 13, 2026
両国を取り巻く戦略環境が厳しさを増す中、日韓関係、日韓米の連携の重要性はますます高まっています。
李大統領との間では、日韓両国が地域の安定に連携して役割を果たしていくべきとの点を確認しました。… pic.twitter.com/38ozZqyjFF
Ms Takaichi, who used to drum in a student heavy metal band, added the leaders played two K-pop songs - "Dynamite" by megastar boy band BTS and "Golden" from the US Golden Globe-winning animated film "KPop Demon Hunters".
A clip of the pair showed Ms Takaichi drumming energetically, with a huge smile on her face.
Mr Lee admitted that "it was a little awkward at first, but the more I tapped, the more the sound came together".
"We shared the same intention to keep the rhythm even when the beats were slightly different.
"We will work together with one heart to build a future-oriented relationship between South Korea and Japan."
The leaders visited one of Japan's oldest temples in Nara.
