This study is testing a new medicine called NMRA-335140 to see if it helps with major depression symptoms in people with Bipolar II Disorder. Bipolar II Disorder is a mental health condition that causes extreme mood swings from high (hypomania) to low (depression). The study will last for about 3 months and includes three parts: a Screening Period (up to 28 days), a 6-week Treatment Period (with NMRA-335140 or a placebo—a fake pill), and a 6-week Safety Follow-up to make sure participants are okay. A placebo is used to see how well the real medicine works compared to no treatment.

• Participants need visits over about 3 months.
• There's a 50% chance of getting the real medicine.
• Safety checks will be regularly conducted.

To join, participants must have a current depression episode confirmed by a doctor, and their depression symptoms must have lasted between 4 weeks to 12 months. However, those who have failed previous treatments or have certain other mental health issues may not qualify. Safety is a priority, and people who are currently suicidal or have serious mental health risks are not eligible.