During December 2025, Naru focused on enhancing the RegExp.lastIndex documentation within the mdn/translated-content repository. Naru improved the clarity and natural phrasing of the English documentation and contributed a Japanese localization, collaborating with other contributors to ensure accuracy and consistency. The work involved technical writing and documentation skills, using Markdown to deliver clean, well-structured commits. By updating the ja/web/javascript/reference/global_objects/regexp/lastindex/index.md file, Naru strengthened the localization workflow and supported MDN’s multilingual developer experience. Although the scope was limited to a single feature, the contribution demonstrated attention to cross-language quality and reinforced collaborative documentation practices within the open-source project.