In the Japanese contemporary literature on teacher education reforms, the term “Shishitsu-Nouryoku (Trait-Competency)” is very commonly used. Apparently, this term is unique; it is rarely used in fields other than teacher education. I will argue in this paper that the term is a vague buzz-word, but, at the same time, it has the potential to capture the learning and development of individual teachers in a holistic manner. I will first explain why “trait” and “competency” are both ambiguous and unscientific terms, and the issues entailed in artificially differentiating the two. Lastly, I will introduce a teacher education theory of a Dutch teacher educator, Fred A. J. Korthagen, to back up my argument that there is a certain significance in looking at teachers’ “traits” and “competencies” together. I conclude my article by giving a few suggestions to the current Japanese teacher education reforms based on the arguments given.