The current paper reviews previous research on the acquisition of Japanese language sounds and pronunciation skills of second-language learners of Japanese, focusing on both segmental and suprasegmental features. We first provide a brief overview of Japanese language sounds. Studies based on comparative analysis of segmental features in Japanese and learners’ native languages are then discussed, followed by a review of recent studies involving a range of techniques, including acoustic analysis, cross-sectional and time-series experimental designs to explore the acquisition process and factors affecting it. In addition, we examine research on the production and perception of Japanese lexical accent, and the relationships between them. Based on this review, we propose that the rhythmic unit, mora, a typologically unique feature of Japanese, presents significant learning challenges for second-language learners, because it affects the perception and production of segmental features such as long and short vowels, double consonants, and syllabic nasals as well as the Japanese lexical accent. Finally, we examine previous research examming second-language learners’ pronunciation skills. We propose that insufficient attention has been paid to this issue, warranting future investigation.