This study aims to test **Roluperidone**, a new drug, on adults with schizophrenia, which is a mental health condition that affects how a person thinks, feels, and acts. The study has two parts: Phase A focuses on understanding how effective and safe Roluperidone is in treating negative symptoms of schizophrenia, like lack of motivation or interest. Phase B looks at how often symptoms return when using Roluperidone compared to other antipsychotic (anti-mental illness) medications. **Key Points:** - The study is for adults aged 18-55, with stable schizophrenia symptoms. - Participants will stop taking other psychotropic (mind-altering) medications. - The study requires informed consent and a caregiver to assist and provide information. Participants must not have certain other mental health conditions, substance use issues, or be using specific medications. Women must not be pregnant or planning pregnancy during the study. Participants will be monitored for any serious side effects or health issues. If you are considering joining, it's important to discuss this with your healthcare provider.