<p>Bilibili has emerged as a hub for anime enthusiasts, particularly the youth, fostering a community rich with nostalgic childhood memories. Fans have reignited a collective sense of nostalgia through the creation and consumption of fanvids, thereby rediscovering the cultural significance embedded in childhood animations. Using mediated memory theory as a framework, this study focuses on anime nostalgia communities on Bilibili, examining their digital memory practices centered around the Digimon series. Research has demonstrated that nostalgic videos serve as memory artifacts, bridging personal and collective recollections and thereby facilitating the formation of fan identities and the delineation of social groups. Evidence suggests that digital platforms foster dynamic memory networks through algorithmic recommendations, bullet screen and interactive discourse in comment sections, enabling users to reconstruct personal narratives and cultivate a sense of intergenerational belonging within digital environments. Hardcore fans who pursue in-depth research and sentimental fans who emphasize emotional resonance often debate “what constitutes genuine childhood memories.” This clearly shows that the process of constructing collective memory on the internet is highly complex, perpetually intertwined with negotiation, collaboration, and conflict. This study not only expands the application of media memory theory in non-Western fan participatory cultural environments, but also provides empirical evidence for understanding the reproduction mechanism of collective memory in the platform era.</p>