Jun Takahashi is a principal researcher (leading researcher) in Advanced Research Laboratories, Nippon Steel Corporation, Japan. He obtained Bachelor and Master degrees in Physics at Tohoku University, Japan. He joined Nippon Steel Corporation in 1989 and begun his research on development of semiconductor materials. He received Doctor’s degree from Tohoku University in 1997. Then he started his new research on characterizations of steel materials by using atom probe tomography (APT) in 2001. He studied at Max-Planck-Institut für Eisenforschung (MPIE), Germany, for one year in 2011-2012. His primary field of research is elucidation of the relationships between mechanical properties and microstructures of steels. Hydrogen visualization using APT is also one on his researches. He has published more than 100 papers in refereed journals and conference proceedings and has applied more than 100 patents.