The purpose of this study was to foresee the future development of mindfulness by reviewing its multifaceted nature and the phases in which it has evolved in Japan since the beginning of the 21st century. This study set up three phases and revealed how each phase apprehends the conceptual entity of mindfulness. The description of each phase was (1) mindfulness as a clinical intervention method, represented by Mindfulness-based Stress Reduction (MBSR); (2) mindfulness as an ideological concept captured in a sociopolitical context; and (3) mindfulness as the sati, which represents the original meaning of mindfulness indicated in the Pali Canon of Theravada Buddhism. This review extracted the invaluable contribution of mindfulness as a clinical methodology, although significant attention should be given to its value-neutral individualized feature so that mindfulness may obscure the ongoing sociopolitically structured injustice issues in our society. For future implications, the study showed the importance of scrutinizing the meaning of sati and integrating it into mindfulness so as to establish a meaningful approach that informs the value of social justice.