This study is a single-blind, multicenter, randomized, controlled crossover trial. All subjects who met the inclusion and exclusion criteria will be randomly assigned to the App first group (fAPP) and or a waitlist crossover group (dAPP). Due to the intervention's nature, this will be a single-blind study in which the results will be assessed blindly but participants will be aware of their group assignment. Participants assigned to fAPP group will use the App initially for 28 consecutive days (T1). During T1, participants assigned to the dAPP arm will maintain the usual treatment. After T1, during the next 28 consecutive days (T2) without washout period, dAPP will use the APP, and fAPP will only maintain the usual treatment. We assumed that there would be no carry-over effect as the App utilized in this study is not a curative treatment but rather a tool for relieving stress in patients with depression. Therefore, we decided to use a cross-over design without a wash-out period.

The three University Hospitals in the Republic of Korea participating in the study will recruit depressive patients for applying the App. The Korea University Guro Hospital and Korea University Anam Hospital are in the inner center of the Capital, and Korea University Ansan Hospital is in Ansan city, outskirts of the capital area. Each hospital is a general hospital, and the Korea University Guro Hospital will lead the ASMA-D study as. For patient recruitment, 96 patients (48 interventions and 48 controls) in the Korea University Guro Hospital and 60 patients (30 interventions and 30 controls) in each from Korea University Anam Hospital and Korea University Ansan Hospital will be expected.

Screening will begin for those who are interested in advertisements posted in the participating hospital among the depressive patients who visit the hospital. After interested patients will contact the research team. the patients will be screened for eligibility according to the above-described criteria by the psychiatrist. After eligibility is confirmed, details of study will be explained to potential participant. Once participant agrees to participate, Informed consent is obtained, patient is enrolled, and randomization only occurs after enrollment.

Successful volunteers will be randomly assigned to the fAPP of dAPP. Randomization is conducted using block randomization by each clinical center. To prevent bias towards one treatment group, eight patients will be configured in blocks and will be randomly assigned to groups fAPP and dAPP within each block. For consistent allocation, randomization will be done using a pre-built program. This program is created by Korea University Guro Hospital to blind the researcher from the information of assignment in advance.

Assessments are obtained clinician rating scale and self-rating scales during hospital visits. Assessments conducted at the hospital visit were acquired at the baseline (V0) and every two weeks (V1, V2, V3, and V4) during T1 and T2. The baseline assessments will be collected when participants are enrolled and include sociodemographic and clinical characteristics. All instruments have been translated to Korean with reliable psychometric properties. The data collection process implanted in the evaluation module of the mobile App will be activated through an ID issued after enrollment and randomization.