Is teaching emotional labor? Are teachers selling their own emotions in exchange for money? To examine these questions, this paper examines teachers' emotion expression in teaching. Most previous studies have assessed teachers' emotional experience using interviews, and have reported that because teachers manage their own emotions, teaching is emotional labor. However, these studies have not examined teachers' emotion expression mediated by their interaction with students. This paper uses multiple methods, combining observations of and interviews with three secondary school teachers, and introduces the concept of emotion management and self-disclosure. Teachers induced enjoyment and spontaneously expressed it to help students concentrate on learning. Whereas, when students showed teachers their interest in learning, participated positively in the class and increased their understanding toward learning content, teachers expressed positive emotions such as joy and wonder. The teachers' negative emotions were drawn out by students' speech and behaviors that showed passivity and an impolite attitude. Teachers tended to express negative emotions to control students and help them concentrate on learning. However, before teachers expressed strong negative emotions such as anger, they tried to express irritation in a controlled way, and suppressed their anger as much as possible. Teachers indicated that frank expressions of emotions formed caring relationships with students based on reciprocal emotional understanding. Results indicated that teachers consciously and unconsciously expressed negative emotions based on their caring professional identity and personal beliefs and values. Therefore, teachers appear to disclose their genuine emotions according to the context or situation. Overall, teachers did not manage their emotions or alter their values based on the school's request; they induced, suppressed, and disclosed their own emotions based on their professional autonomy and personal beliefs. Teachers' emotional practice can thus be considered an autonomous, discretionary, and professional activity of caring rather than emotional labor. (Contains 7 tables and 3 notes.)