Higher Education Institutions (HEIs) worldwide have stated their commitment to sustainability and aim to successfully integrate Education for Sustainable Development into their teaching. However, approaches, concepts, and execution vary significantly across institutions. Research has shown the potential benefits (e.g., the increased likeliness of goal achievement) of incorporating the Sustainable Development Goals (SDGs) in HEI curricula. Yet, the presence of the SDGs in teaching mainly relies on individual initiatives. Only a small number of universities have taken the step to systematically introduce a mandatory SDG class for all of their students. One of these universities is the Toyohashi University of Technology, located in Japan. This paper presents qualitative research conducted in 2024 that consists of reviewing teaching materials and interviewing professors and administrative staff at the Toyohashi University of Technology. It shows how the SDG class is structured and implemented, what teaching methods are used, which training educators received, and what role the SDGs play outside the mandatory class. Particular emphasis is given to the problems perceived by the professors after the university’s president introduced the mandatory class. The aim of this paper is to critically examine how a top-down approach to mandatory sustainability teaching functions in practice and to explore the practical and pedagogical challenges involved. The results will contribute to the understanding of top-down approaches and are relevant to educators, researchers, and other university actors aiming for an accelerated integration of sustainability into university teaching.