This study aims to identify the characteristics of nationalism in Japanese cyberspace starting in the late 1990s and especially focusing on the emergence of the Net Right and its impact on Korea. The Net Right signifies ultranationalistic texts against ethnic Koreans and Chinese on the Japanese internet bulletin board. They emerged in the early 21st century and had differentiated from previous right-wing activism in Japan based on its different theoretical backgrounds. During the 20th century, nationalism in Japan developed as a basis of constructing the modern Japanese state against the west, and national pride functioned as a tool for economic growth. Japanese nationalism in these days, however, is amplified with massive information exchange and the sharp drop in the cost of producing, storing and distributing digital content. The dominant cultural purpose of the den of the Net Right is amusement and not aberration. But the spreading of mutually understood negative ideations is not desirable because it contributes to the development of nationalistic fervor and aggressive tones to a broader national audience. The Net Right starts to influence Korea-Japan relations including territorial disputes and their soft power policies. In case of Dokdo, the Net Right accumulated their own nationalistic discourses and mobilized large groups of people by using websites and social media. In spite of their efforts, the influence for real politics is still limited. On the other hand, cyber nationalism is vital to the popular cultural sphere in the rapid globalization and transnational processes of cultural production, consumption, and practices. Government initiatives to promote digital content distribution increased vigilance of other cultures or even stimulates cyber nationalism.