Hisao Nakai (1934-2022) surprised many experts with his prolific publication of papers ranging from meticulous therapeutic engagement and observations to original research. The "theory of the remission process of schizophrenia" is a representative example of Nakai's research and theories. The significance of Nakai's theory of the remission process is that it let the world know about the existence of schizophrenia's remission process, which had not been previously recognised. Additionally, Nakai's discovery of the "critical period" was significant and his detailed description of the same, which marks the beginning of the remission process, is widely considered to be fundamental. Nakai closely followed common phenomena that appeared accidentally, and he plotted the reactions of the autonomic nervous system, patient's dream content, and drawing content on a chart to show, for the first time, the clear emergence of a "critical period," and demonstrated the crucial role of the remission process. Nakai explained how the process progresses sequentially from the "critical period" to the "early remission period" and the "late remission period." He identified many specific indicators and discovered a great significance in innovative therapeutic engagement in each of these periods. Nakai's findings are supported by meticulous clinical observations and are free from simplifications that stem from simple theorization. In particular, close observation of the remission process was conducted with full engagement and concern of the therapist, without which, the remission process would not have been visible.
Keywords: critical period; naturalistic approach; patient's drawing; progress chart; schizophrenia.
© 2023 The Authors. Psychiatry and Clinical Neurosciences Reports published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Psychiatry and Neurology.