Japan has been playing a leading role in the field of X-ray astronomy since the dawn of this field by launching satellites namely "HAKUCHO" (CORSA-b), "TENMA" (ASTRO-B), "GINGA" (ASTRO-C), "ASUKA" (ASTRO-D), and "SUZAKU" (ASTRO-EII), which is currently in operation. The ASTRO-H is the sixth X-ray astronomy satellite following these predecessors.