This study presents a comprehensive morphological and socio-historical analysis of the Korean second-person pronoun Jane (자네), tracing its evolution from a medieval reflexive form to a highly specialized kinship term and, further, to a potent cultural symbol. Through an integrated approach combining historical linguistics, pragmatics, sociolinguistics, and linguistic anthropology, the paper argues that Jane (자네) has undergone a process of cultural-semantic metamorphosis. Rather than fading into obsolescence, it narrowed functionally to occupy a precise relational niche—primarily as an address from parents-in-law (cheobumo, 처부모) to son-in-law (sawi, 사위)—while simultaneously accumulating dense indexical meanings. As its everyday use contracted, Jane (자네) became a marked symbol of traditional authority and hierarchical integration, enabling its regeneration across pedagogical, media, literary, and public discourse fields. The paper thus challenges conventional measures of linguistic vitality, proposing instead that a form's persistence may be sustained through distributed symbolic utility rather than frequency of colloquial use. By modeling Jane (자네)'s adaptive trajectory, this study offers broader insights into the mechanisms through which language retains historical social structures and negotiates cultural continuity amid modernization.