Systems for water and material cycles were proposed for Sustainable Marine City (SuMaC) which is a fictitious reclaimed island (800-900 ha) on Osaka bay coastal zone with 39,000 residents. In the water cycle system, highly purified water is supplied at 14,100 m^3/day for drinking, cooking, and bath. While, recycled water originated from domestic wastewater and rainwater is used at 4,470 m^3/day for flushing toilet, laundry, and others. In the waste recycle system, waste food of 7.2 ton/day, branches and weeds of 3.0 ton/day, and waste sludge of 3.2 ton/day are digested to methane at 1,300 Nm^3/day. Combustible wastes are incinerated at 17 ton/day for waste power generation with methane. Other domestic wastes of 19 ton/day containing papers of 12 ton/day are processed for reuse and/or recycle.