NJS Consultants Co. Ltd. (NJS) was established in 1951 in Tokyo, Japan, and is a major independent international multidisciplinary engineering consulting firm, specializing in environmental engineering, water supply, sanitary and civil engineering, together with institutional development, training and financial management activities related to environmental projects.

As one of the pioneering sanitary engineering firms in Japan with almost 60 years of worldwide experience, NJS enjoys a reputation for providing technical excellence and a superior quality of work to its clients. Having carried out almost one-third of the sewerage and sewage treatment schemes in Japan as the country invested heavily in urban sanitation upgrading in the 1950s and 1960s, NJS is now rated as one of the top Japanese consulting firms providing water and wastewater consultancy services to its worldwide clients.

The NJS headquarters and corporate offices are located in Tokyo, with 37 branch offices throughout Japan. The NJS International Division provides services outside Japan, and has regional liaison offices in Asia in Pune, Colombo, Kuala Lumpur and Manila; in the Middle East in Dubai and Muscat; in Africa in Tripoli; as well as in North America in Los Angeles and in Latin America in Lima, and typically has some 30 project and field offices worldwide at any one time.