To explore factors that minimize lunch waste in Tokyo elementary schools and to consider how such factors can be modified and applied in US schools.Focused ethnographic study using interviews, observation, participant observation and document review. Data were analysed using thematic analysis.Tokyo, Japan.Five school dietitians participated in the study. Data collection methods included in-depth interviews, observation of nutrition education lessons, participant observation of school lunchtime and review of relevant school documents (e.g. lunch menus, food waste records).Five themes emerged from the analysis: (i) reinforcement of social norms to eat without waste; (ii) menu planning to increase exposure to unfamiliar and/or disliked foods; (iii) integration of food and nutrition education into the school curriculum; (iv) teacher lunchtime practices related to portion sizes, distributing leftover food and time management; and (v) engagement of students in reducing school lunch waste. Practical and tangible applications to US schools include measuring and reporting lunch waste to influence social norms, teaching students about the importance of reducing food waste, offering flexible school lunch portion sizes and providing students with meaningful opportunities to contribute to solving the problem of school lunch waste.Japan offers a model for minimizing school lunch waste through a holistic approach that includes factors that operate at and interact across multiple levels of society. Modifying and applying such an approach in US schools is worth considering given the urgent need to address food waste in order to support healthy diets and sustainable food systems.