During May 2025, Kim SeongHyun contributed to the se-sac/sesac-01 repository by creating and updating documentation to support class onboarding and data accuracy. He developed new README.md files for both class01 and class02 homework within the KimSeongHyun directory, using Markdown to ensure clarity and consistency. His work focused on initializing class records and correcting student information, specifically updating the entry for student '02' to maintain data integrity. While the scope was limited to documentation and did not involve bug fixes or code features, the updates provided a reliable foundation for future contributions and improved the repository’s organizational structure.