Study procedure
T1–T3
Information about the study will be communicated to each department of each research institution through postings, in-hospital e-mails, websites, and other means. The contact information of the research office will be clearly indicated. Patients who visit each research institution during the study period and wish to participate in the study after recommendation by their attending physician, and those who wish to participate in the study on their own and whose attending physicians determine that their participation is appropriate, will be selected from among those who meet the eligibility criteria and who do not meet the exclusion criteria. For patients who meet the eligibility criteria but not the exclusion criteria, the therapist will provide a detailed explanation during the preliminary interview and obtain their consent to participate in the study. Once consent is obtained, the therapist will confirm the eligibility and exclusion criteria other than the BDI-II score and ask the research assistant to administer questionnaires. The research assistant will ask the participant to fill out the BDI-II questionnaire and transfer the data (entry number, anonymized subject information, and T1 outcome data) to the data center with the entry number written on the case registration form. If the BDI-II score is 16 or higher, the patient will be registered in this study. Once a patient is registered, the registration will not be cancelled (deleted from the database) except in the case of withdrawal of consent, including refusal to use the data for research purposes. In the case of duplicate enrollment, the first enrollment information will be used.The intervention and each assessment scale will be evaluated using the following process (Figs. 
Flow of registration and evaluation for this study. Participants will be randomized 1:1 into the intervention group or the waiting group. Participants will have seven intervention sessions, delivered over 4 months. Outcome measures will be evaluated at three times (T1–T3) in the intervention group and four times (T1–T4) in the waiting group
SPIRIT figure: Schedule of enrollment, interventions, and assessments. Participants in the intervention group will be asked to complete questionnaires at three times (T1–T3). Participants in the waiting group will be asked to complete questionnaires at four times (T1–T4). They will complete questionnaires in the waiting room, at the examination room after the BA session at the facility, or at home. Research assistants will check the responses and ask participants to supply any missing data. The research assistants will collect the completed questionnaires. They will transfer the data from the questionnaires to the data center.