Throughout Japan's nine years of compulsory education (six years of elementary and three years of junior high school), music remains a mandatory subject governed by the national Course of Study. The curriculum aims to foster students' ability to engage with music and sound in society through performance and appreciation, rather than focusing solely on professional training. However, a 2012 national survey highlighted a critical deficiency in perceived relevance: only 47%of students deemed music classes "useful in daily life or society." This failure was frequently linked to an overemphasis on technical skills and significant variability in teaching quality. This challenge persists despite recent curriculum revisions.This action research was thus initiated to fundamentally transform this perception, specifically targeting the junior high level. The project trialed an innovative pedagogical approach, "Musical Playful Learning," which reframed instruction to prioritize intrinsic engagement and the fundamental essence of music. The study involved a large cohort, including 900 junior high students and 80 elementary students.Implementation of this approach yielded significant positive outcomes: Students exhibited elevated expectation and proactive participation in lessons. They further reported an increased sense of holistic personal growth through public performance and recitals. Crucially, written assessments confirmed a measurable deepening of their musical understanding.These results were achieved despite the complexity introduced by external factors like Vocaloid, AI, and mobile devices, which create a musical environment disconnected from school. Additionally, the Japanese cultural tendency toward emotional restraint poses a challenge to musical expression. Nevertheless, this study demonstrates that conveying music's inherent appeal in the classroom is highly achievable. Sustained success ultimately hinges on continuous teacher competency development and dedicated curriculum innovation.