The Latin script is closely associated with phonemic writing, characterised by the systematic use of monosegmental signs. While this applies to various writing systems, the paper discusses its applicability to rōmaji, the Latin script adapted for Japanese. Initially employed for romanising Japanese words, rōmaji has evolved to serve multiple functions, including abbreviations and loanword notation. A survey of rōmaji usage in the Balanced Corpus of Contemporary Written Japanese revealed that only about 16.04% of rōmaji instances were for romanisation. This result indicates that its phonemic role is limited. Further research is necessary to understand its current functions better.