AbstractSince 2020, English has become a compulsory subject in Japanese elementary schools, and grade three to six teachers need to teach English despite their limited knowledge of English teaching. Most teacher training programs are transmitting styles and do not always meet the difficulties of individual teachers in English teaching. This research focuses on teacher self-reflection as an alternative to support teachers’ self-development in addition to training programs. Two Japanese elementary school teachers reflected their English lessons and how their possible selves shaped their future lessons. They recorded and reflected six lessons from a textbook unit and recorded another six lessons from a different unit. The recorded lessons were transcribed, and the reflections were coded to generate theories that revealed their possible selves. Their explanations for reflection and validation were obtained from interviews. One teacher’s Ought-to self shaped his future team-teaching practices with the assistant language teacher. The other teacher’s Ideal self modified her routine activities to meet her ideal duration for the activities. The teacher participants’ self-reflection revealed their possible selves, which served as a basis to modify their future English lessons to meet their ideals. This study recommends that this mechanism of individual reflective practice be encouraged as part of the teacher development program in addition to the existing teacher training.