Our idea emanates from the International Symposium on Sustainable Urban Environment 2007（ISSUE）[1] which was held, with support from the Tokyo Metropolitan government and the Ministry of the Environment of Japan, at Tokyo Metropolitan University, having the theme of producing a sustainable urban environment. In order to offer a concrete image of our suggestions, we were then provided by our sponsoring organization, the Tokyo Metropolitan University Center for Academia/Industry/Public Collaboration, with funding for FY 2008 and continued to work on more detailed studies on this subject during FY 2009 and 2010.

The water city for Koto Ward as one of the worst lower-lying land area in Tokyo was examined as the case of higher density city area. The case 1 shows the small city size and the planned population, which is set at its current size between 27,000 and 30,000, is three times the size of that of its neighboring communities (8,000 to 10,000 people) and various city functions such as the shopping center, office area and so on are included while the case 2 which function is limited to residence area was examined for the precise feasibility studies such as the engineering aspect, the financial aspects and so on.

Furthermore, we have suggested the "Coastal Aqua-Village System" for the recovery of Arahama and Kesennuma areas destroyed by huge tsunami in March 11, 2011. This "Coastal Aqua-Village System"is expected to see application in establishing new measures and infrastructures to secure the living environment against natural disasters for South Pacific Islands, Asian nations and American as well as European countries that suffer from similar problems. The study for Arahama is the case of low density residential and agricultural area close to the coastal region while that for Kesennuma is the recovery project for fishery town with residences along harbor.

• Case Study 1: roject of the soft-landed water city "WATERPOLIS" in Koto Ward, Tokyo
• Case Study 2: Urban Redevelopment for High Density Residential Areas in Koto Ward, Tokyo
• Case Study 3: Reconstruction Scheme for Arahama areas in Northeast Japan
• Case Study 4: Recovery Project for Destroyed Kesennuma in Northeast Japan
• Case Study 5: Singapore Water City