Extensive reading (ER) programmes are based on Krashen’s claim that comprehensible input and free voluntary reading (FVR) are considered crucial to language acquisition. However, it faces unpopularity due to L2 curricula prioritising language skills, grammar, translation, and vocabulary over fluent reading. In Japan, where grammatical analysis training and vocabulary acquisition are essential due to the significant distance between the learners’ L1 and L2, debates on ER’s effectiveness remain unresolved. Based on these conflicting arguments, this study examined the narratives of two EFL learners in a long-term ER programme at a Japanese university to gain a comprehensive understanding of their experiences. It explored the participants’ detailed descriptions of their FVR experiences and investigated factors influencing changes in their reading proficiency and attitudes during the programme. Using a case study research design, qualitative data collected from their reading records, online interviews, and observations of their classroom and independent reading over 3.5 years were thematically analysed. Their narratives demonstrated that the key factors in improving their reading proficiency and attitudes were enjoyment, freedom to choose books, a pressure-free environment, intrinsic motivation, and self-efficacy. Moreover, the participants considered grammar and vocabulary study as complementary to ER, rather than competing with it.