Ryunosuke Koike was born in 1978 in Yamaguchi Prefecture, Japan. A former Buddhist monk of the Jodo Shinshu School, he is now master of the Tsukuyomi Hall, previously known as Tsukuyomi Temple, in Kanagawa Prefecture. He is internationally renowned for his accessible, yet comprehensive books on Zen and Buddhism, which have sold over a million copies in Japan alone and have been translated into many languages.