Nitrogen evolution research has been widely carried out in Japan after the Forth International Conference on High Nitrogen Steels held in 1995 in Kyoto (HNS1995). The first research forum on nitrogen evolution research has been started in The Japan Society of Corrosion Engineering in 1996, followed by a series of research forums in the Iron and Steel Institute of Japan (ISIJ). In the meantime, a pressurized electro-slag remelting furnace was newly developed in National Institute for Material Science in 1998. A new research group regarding the availability of nitrogen on the improvement in steel properties has been started in ISIJ in 2004. Current research activities of the group cover the fabrication of HNS such as mechanical alloying, pressurized ESR and nitrogen absorption, evaluation technologies of HNS such as microstructure and precipitation behavior of nitride, mechanical properties, corrosion properties and physical properties, joining/welding technologies. As one of the applications of HNS, Ni-free high nitrogen steels with high strength, anti-corrosion, non-magnetic properties are very attractive in the fields of bio/medical ones as anti-Ni allergy material. Recent research activities including some topics mentioned above will be discussed.