As the blockbuster which monopolized the comic selling ranking, Koyoharu Gotoge's Demon Slayer became the most popular manga, animation and movie in 2020. The story itself seemed simple, however, if one asked the reason why Demon Slayer became viral, it may not be as simple as it seemed. This article argues that the huge success of Demon Slayer could not simply be due to the marketing strategy, but instead, it provides an approach to the culture studies in the national character of the Japanese from their innermost aesthetic view. By discussing two concepts "Mono no aware (物哀)" and "Gyokusai (玉碎)," this article aims to explore how these two concepts became the infrastructure of Demon Slayer. How do the conversations and images in Demon Slayer echo with Japanese's specific national character and aesthetic values of the Japanese? What values were revealed and prevailed others? The author extends the analysis towards the studies of Japanese culture, trying to explore a plausible approach toward to the success of Demon Slayer and the Zeitgeist it portrayed or coincided.