The results of this study provide encouraging support for the feasibility of IOT for helping participants with schizophrenia who are enrolled in an OT program at Japanese psychiatric hospitals. The retention rate of the participants in this study was very high; 66 of 68 patients (97.06%) who agreed to participate were successfully engaged and completed the IOT arm from hospitalization to discharge or 3 months following hospitalization. This suggests the implementation of IOT did not have any adverse effects on patients with acute schizophrenia in the IOT program, and that IOT could be feasible for use in a Japanese psychiatric hospital setting. The study also provides support for the effectiveness of the IOT in improving cognitive functioning (BACS-J) and other outcomes including intrinsic motivation (IMI-J), medication adherence (MMAS-8), and treatment satisfaction (CSQ-8J) in patients with schizophrenia. However, the results of this study may only suggest not so much the effectiveness of the IOT alone but the effectiveness of the adding IOT to GOT on outcomes. Although patients in the GOT alone group also showed the trend to improve several outcomes, the greater magnitude of outcomes improvements in the GOT + IOT were demonstrated compared with those in the GOT alone. For greater improving outcomes, it may be important to implement not only the IOT alone but also the adding IOT to GOT.