A star-studded cast of world leaders will gather in Hiroshima between May 19th and 21st. Joe Biden will deliver a speech in front of the A-Bomb Dome, focussed on nearly eight decades of reconciliation between the U.S. and Japan. Prime Minister Fumio Kishida will warn that the threat of nuclear conflict looms large, especially in the wake of Russia’s invasion of Ukraine. And President Zelensky will play a cameo role, delivering his address by video link from Kyiv, which has recently been subjected to another barrage of Russian drone and cruise missile attacks. Then, at a grand banquet, the big names of the G7 from Europe, the U.S. and Canada will be joined by Narendra Modi from India, as well as the leaders of Indonesia, Brazil and Comoros. I expect the sushi to be magnificent.  Yet observers who want to understand what this G7 summit means for China should focus their attention on the performance of a high profile guest: Yoon Suk-Yeol, the president of South Korea.