Atsushi worked on the weseek/growi repository, focusing on API surface reduction and documentation cleanup as part of the API v3 deprecation initiative. He removed the obsolete 'Staff' endpoint from the API definition and updated related Swagger/OpenAPI documentation, streamlining the migration path for client applications. Using JavaScript and TypeScript, Atsushi aligned the backend implementation with the new deprecation strategy, ensuring maintainability and reducing support overhead. His work emphasized precise, commit-level changes that improved repository hygiene and traceability. The updates addressed both feature removal and bug fixes, demonstrating a methodical approach to API development and documentation management within a short timeframe.