We developed and tested a teaching case and teaching note on the challenges that a small sustainable fashion brand faces when implementing a circular business model. We target bachelor and master students of international business, entrepreneurship, strategic management, circularity/sustainability courses. This teaching case challenges students to think about how circular business models can contribute to sustainability and highlights opportunities and barriers to adopting circular strategies. The case is based on publicly available sources and interviews with sustainable fashion brand Kuyichi. The main learning objectives for students are: 1) to understand the concept of circular economy (CE) and how circular business models differ from linear business models; 2) demonstrate in what way circular business models can contribute to sustainability; 3) evaluate rental and/or resale business models and the challenges and opportunities involved; 4) make recommendations on adopting circular strategies or business models that support the transition to a circular economy. The teaching note highlights academic and practitioner literature, such as circular business models (Bocken et al., 2016; Circle Economy, 2021; Lüdeke-Freund, Gold, Bocken, 2019), strategies (Konietzko et al., 2020), transition theory (Geels, 2002; Nambisan and Baron, 2013), organizational inertia (Sydow et al., 2009) and dynamic capabilities (O’Reilly and Tushman, 2004; Teece et al., 1997), and makes suggestions for classroom discussion and assignments. The teaching case and note will be published as a free case with The Case Centre. We are grateful for the support of the Dutch Research Council, RAAK.PRO03.038, that made the development of this case possible.