These are the slides from the 134th GIST Seminar, hosted by GRIPS - National Graduate Institute for Policy Studies & GIST - GRIPS Innovation, Science and Technology Policy Program, Japan. Presenters: Kathleen Gregory (CWTS, Leiden University, NL) & Andrew S. Hoffman (CADS/CWTS, Leiden University, NL) Moderator: Honami Numajiri (GRIPS, JP) Abstract As scientific research becomes increasingly data-intensive and collaborative, research data has emerged as a critical asset. This shift necessitates specialized expertise to manage, share, and reuse data effectively across its entire lifecycle. In response, new professional roles called data stewards, dedicated to research data management (RDM), have emerged as critical professional positions in the research ecosystem to complement traditional research positions. Data stewards are responsible for the planning, collection, organization, and management of research data throughout its lifecycle. This emerging profession requires individuals with specialized skills who can bridge technical data expertise with domain-specific research knowledge, forming a new professional domain often referred to as "Data stewardship". Leiden University has been at the forefront of formalizing the data steward profession within academic institutions. It has established a structured community known as the "Research Data Management Community" at the university, where data stewards collaborate with researchers and support staff from all faculties and central services. This community brings together professionals from all faculties and central services to exchange knowledge and experience, develop best practices, and contribute to the evolution of data management services across the university. This seminar will explore the emerging profession of data stewards through insights from the Centre for Science and Technology Studies (CWTS) at Leiden University. Mr. Andrew S. Hoffman and Dr. Kathleen Gregory will share their experiences as data stewards and in building Research Data Management Communities. They will discuss both theoretical frameworks and practical implementation strategies that have proven successful in the European context. The seminar aims to stimulate discussion on how Japanese research institutions can develop effective data stewardship capabilities and communities of practice. It will explore how these new professional roles are reshaping scientific infrastructure and creating opportunities for more open, transparent, and collaborative research environments.