RIKEN and Japan Synchrotron Radiation Research Institute (JASRI) have completed Japan's first X-ray free electronic laser (XFEL) facility, named SACLA, which had been under construction at Harima Science Garden City since 2006. XFEL is said to be the “dream light,“ a completely new form of light for humankind. What kind of light is XFEL? What will it make possible? What distinguishes SACLA from competing XFEL facilities in the United States and Europe? These are the questions that are answered in this program.