This study aims to identify how the professional teaching of Basic Korean Literacy begins and develops by analyzing the experiences and perceptions embedded in the narratives of teachers as educational agents. In order to achieve the purpose of the study, the researchers conducted in-depth interviews with 10 elementary school teachers who were tutoring “reading underachievers” after school in North Jeolla Province. Their narratives, obtained from two-month interviews with the researchers, are the most important sources of this study. These data were analyzed by the thematic analysis and the causal chain analysis. The main research results show that these teachers began to actively cultivate their “specialty in teaching elementary level reading” after encountering their fateful reading underachievers and face serious reading problems of the learners. Also, teachers were well aware that reading underachievers were not confident in their learning, which may cause many difficulties throughout their school lives. Because of their poor academic performance, underachievers may not be likely to have a good relationship with their peers. Learners who fail to read properly will not be able to keep up with subsequent Korean curricula or other subjects. Thus, the primary role of elementary school teachers is to find reading underachievers as early as possible and minimize learning deficits by finding the most appropriate teaching methods to solve their problems. This study suggests that teaching reading underachievers is as important as defining one’s identity as an elementary school teacher.