Abstract

Objective: In-person counseling faces limitations in timing and geographical accessibility, often causing adolescents and

young adults (AYAs) to miss timely psychological support. With the advent of large language models (LLMs), the mental

health care industry has increasingly focused on developing chat counseling services as supplementary tools to reduce

these barriers. However, existing services have two primary limitations: tendency toward generic advice and absence

of human-like dialogue. To overcome these limitations, this article proposes BetterMood, a human-like AI counseling

service specifically for Korean-speaking AYAs.

Methods: Our design for BetterMood separately addressed the content and delivery of counseling dialogue. For content,

we develop a concern-aware counseling LLM refined through prompt-engineering with a novel prompt derived from collected

counseling data. For delivery, we create a human-like AI counselor that employs a chunk-based streaming methodology

to enable human-like dialogue. We then conducted a user study with 10 adolescents, 110 young adults, and 8

professional clinicians to assess the feasibility and user experience across four domains: (i) interaction capability, (ii) perceived

support, (iii) usability, and (iv) ethical safety.

Results: Our user study indicates that BetterMood’s interactive capabilities, particularly its ability to suggest appropriate

responses, received positive feedback from 90.0% of adolescents, 90.9% of young adults, and 75.0% of professional clinicians.

Stratified analysis revealed that outcomes regarding perceived support and usability of the service differed across

cohorts and initial screening status. Furthermore, independent evaluations by eight professional clinicians demonstrated

moderate agreement for individual ratings but excellent reliability for the aggregated assessment.

Conclusion: Positive user experience and high inter-rater reliability among clinicians support BetterMood’s potential as

an accessible supplementary tool for initial psychological support.

Keywords

Adolescents’ and young adults’ mental health care, AI counseling, concern-aware counseling LLM, human-like AI

counselor, chunk-based streaming