["Japanese Psychological Research, EarlyView. ", "\nAbstract\nEmerging adults' relationships with their mothers and friends serve attachment, affiliation, and caregiving functions. The attachment function provides security. The affiliation function promotes mutual partnerships. The caregiving function involves caring for others. However, few non‐Western studies have examined the degree and role of the three functions. This study recruited 100 Japanese university students (Mage = 20.91 years, SD = 1.35 years, women = 50) and evaluated relationship functions using a narrative method, the Three‐Words Interview. Similar to findings from Western contexts, Japanese emerging adults were more likely to perceive the attachment function of their mothers and the affiliation function of their friends. Additionally, men were less likely to use these three relationship functions in friendships than women. Finally, this study found links between the attachment function of mothers and mental health and between the affiliation function of friends and social competence. These findings emphasize the distinct functions of mothers and friends in emerging adults.\n"]