This paper reexamines the internationalization of Japanese popular music (J-Pop) not through the quantitative increase of English usage, but through the historical transformation of the functional roles assigned to language within musical production. From the "unselfconscious success" of the early 1960s to the contemporary phase of algorithm-driven optimization, Japanese music has repeatedly redefined how language operates as sound, symbol, and structural component. By organizing this process into seven critical reference points and contrasting it with global linguistic strategies (the "Acoustic Transformation" model), this study demonstrates that internationalization was achieved through a series of acoustic and structural solutions. In the current algorithmic environment, language is increasingly detached from semantic content and redefined as a set of sonic features optimized for global circulation. This transformation provides the theoretical groundwork for the emergence of multilingual flow as a structurally necessary next paradigm.