Before Yves Klein became Yves the Monochrome, the now mythical Man of Blue, he had a passion for judo. In 1952, this fascination took him to Japan, where he obtained a 4th dan black belt. A few months after returning to France, Yves Klein simultaneously published Les Fondements du judo and Yves Peintures – the latter considered as his first public action as an artist. His long stay in Japan, punctuated by encounters and discoveries, certainly made a deep impression on Klein, and it continues to compel all those who are interested in his work. After Yves Klein USA and Yves Klein Germany, this book, produced in collaboration with the Yves Klein Archives, relates this founding journey through about 150 documents, photographs and correspondences – some previously unpublished – highlighted through essays by Terhi Génévrier-Tausti and Denys Riout.