His areas of expertise are global hydrology and the sustainability of world water resources including the virtual water trade and water footprint. He was one of the coordinating lead authors for the chapter “Freshwater Resources” of the IPCC WGII AR5. Concurrently appointed as a Special Advisor to the President and a Professor (Integrated Research System for Sustainability Science) of The University of Tokyo. He got many awards including the Biwako Prize for Ecology in 2011. He is the first Japanese AGU Fellow in its Hydrology Section (2014).