He obtained Ph.D. from University of Tokyo. He has published 107 papers in refereed international journals, with total citations of more than 6000. In 2006, he together with team members launched the AKARI space infrared telescope, using which he revealed the dust-hidden cosmic star-formation history. He discovered the most distant black hole host galaxy in 2009. He proposed a new distance measure to measure time variability of dark energy in 2015. His main research interests are dark energy, cosmic re-ionization, and cosmic star-formation history.