Noboru Mitsui worked for an urban development consultancy company, being engaged in consulting on planning of redevelopment of urban areas, urban planning for central and local governments’ administrations, and design supervision on all types of construction including residential apartment houses, office buildings and commercial facilities. He was also engaged in income-generating real estate property development in terms of acquisition, liquidation, and securitization of property investment scheme for a real estate investment firm.

In 2009, he founded District Co., Ltd, rendering services on renovation, project management and construction management. District Co. also tied up from 2012 to 2017 with Futuregement Co., Ltd, a Tokyo-based asset management company primarily for overseas institutional investors, in terms of property/investor sourcing, project arrangement, broking (yen 50 billion in four years) and other related areas.