Research into pedagogical content knowledge (PCK) has advanced over the years. Yet, since most research has developed within specific subject areas, this paper aims to investigate how an expert teacher generates PCK by using various forms of knowledge. This study draws upon the case of an expert Japanese teacher, Mr. T, an educational consultant who leads professional development and school reform efforts by utilising observation of and joint reflection on lessons. Mr. T advances PCK through interaction of stock knowledge from written materials, networks and previous observations, and flow knowledge from the lesson that he observes. Mr. T's case further demonstrates how PCK can engender a democratic and inclusive learning culture within the classroom.