How can we explain the phenomenon of the diffusion of Asian pop culture in the European context?
I agree with Naeim Sepehri. Within the context of cultural globalization, it is also significant to consider the concepts of cultural hybridization and polarization, how particular pop cultures in Asia have been evolving. For example, K-pop and idol culture in the 1990s was influenced by American pop culture, but the Taeji Boys and their competitors hybridized and localized the foreign style, and in the 2000s, they exported their styles to other Asian countries. So, I agree with Naeim Sepehri. It is also useful to analyze these phenomena, historically, comparatively, and critically.
Any pop culture and its representations have a tendency to travel, usually across cultures. As the previous thinkers comment, this travel is also historically and culturally situated. However given the current nature of global consumption, the nature of consumption of such popular representations particularly among youth will suggest many ideas about such traveling cultures.
In my opinion this diffusion is explained not only by the cultural exchange specific to the phenomenon of globalization, which obviously plays an important role, but also by some targeted actions, including financial support, of the governments of some Asian countries, which aim to promote their own popular culture on a global scale (e.g., music, series, movies - see the success of Korean films at international festivals in the last years).
I would suggest reviewing Doobo Shim's works related to this topic. He has a great expertise about K-pop diffusion and his work is available online. I hope that he could see this question and share his thoughts.
History of Asian youth culture exhibitions around 2017-18 in Birmingham, see: asianyouthculture.co.uk curated by True Form projects, former clubbing DJ's and brothers who have collected and preserved historical material. The Museum of Youth Culture has a good London focussed collection of photographs and stories.