Dr. Koichi Yagi worked as a researcher in National Institute for Materials Science (NIMS) (formerly National Research Institute for Metals (NRIM)). He retired from NIMS in March 2006, and he is a private consultant for materials failure accident, and he is working as a senior advisor of National Center for Materials Service Safety (NCMS), University of Science and Technology Beijing (USTB) from April 2009. His working area is safety and reliability of structural metals, life prediction of materials for plant maintenance, failure analysis and so on. When he worked in NIMS, he performed his part as a leader for the development of NIMS structural materials data sheet project including creep data sheet and the development of NIMS materials database. His main research areas were the study on creep-fatigue interaction of heat resistant steels, the study on creep crack growth behavior of heat resistant steels and so on. He has organized many international conferences on creep, for example, 8^th International Conference on Creep and Fracture of Engineering Materials and Structures, Tsukuba (1999), 4^th Japan-China Bilateral Symposium on High-temperature Materials Strength, Tsukuba (2001) and so on. He wrote and edited some books, for example, “Creep Properties of Heat Resistant Steels and Superalloys” which was written together with European and Japanese researchers and published from Springer in 2004. He played the active part for engineering societies, for example, as Japanese representative of JPVRC-EPERC-PVRC committee, Japanese representative of VAMAS (Versailes Project on Advanced Materials and Standards) steering committee and so on.