Idou Endo developed Japanese language support for the lfnovo/open-notebook repository, focusing on expanding the application's accessibility to a broader audience. Using React and leveraging both JavaScript and TypeScript, Idou implemented internationalization features by updating locale files and translating UI strings to Japanese. This work enabled native-language interaction for Japanese users and established a scalable foundation for future multilingual support. Although the scope was limited to one feature over a one-month period, the changes addressed the need for localization and improved user experience for non-English speakers, setting the stage for additional locale integrations in subsequent development cycles.