In response to the increasingly severe climate crisis, the tourism industry has been implementing ESG management and carbon-neutral policies, and sustainability has become the top priority. In this reality, slow tourism is expected to be a sustainable alternative. This study proposes a model of self-expressiveness for slow tourism using the example of Trans-Siberian Railway travel. The main purpose of this study is to analyze the process of the formation of self-expressiveness with the Trans-Siberian Railway experience, its relationship with hedonic enjoyment, and its impact on the life satisfaction of tourists. This research delves into the effects of eudaimonistic identity on life satisfaction via SEM. Moreover, the moderating role that self-expressiveness plays between hedonic enjoyment and life satisfaction is noteworthy, which was assessed based on the bias-corrected (BC) bootstrap method procedure. The data were gathered through an online survey on Instagram and Facebook using a self-administered questionnaire. A total of 210 respondents who had traveled by train in Siberia were used for the analysis. The results indicate that the more Siberian train tourists encountered the flow experience, self-realization, perceived authenticity, and hedonic enjoyment, the greater their self-expression, which had a favorable effect on life satisfaction. In addition, self-expression fully mediated the relationship between hedonic enjoyment and life satisfaction. This research makes a contribution in that it applies eudaimonistic identity theory, which has previously only been applied in the context of leisure, to tourism. Theoretical and practical implications and suggested avenues for future research are also presented.