During his school days, he learned kendo and bushido. A lifelong collector of books, Lee was heavily influenced by Japanese thinkers like Nitobe Inazō and Kitaro Nishida in Kyoto. In 1944 he too volunteered for service in the Imperial Japanese Army and became a second lieutenant, in command of an anti-aircraft gun in Taiwan. He was ordered back to Japan in 1945 and participated in the clean-up after the great Tokyo firebombing of March 1945. Lee stayed in Japan after the surrender and graduated from Kyoto Imperial University in 1946.