Although the phenomenon of social categorization is universal, we argue that different cultures promote different types of categorization and that this is associated with differential language practice. We predicted that, among Japanese (but not among Italian) participants, even a small age difference would be sufficient to trigger spontaneous categorization of other people. We hypothesized that the categorization process would be reflected on a particular pattern of memory bias (i.e., within-category assimilation and between-category contrast). We further tested the hypothesis that specific language styles (i.e., polite vs. intimate) would accompany the age-based categorization effect. In Study 1, we applied the “Who said what?” paradigm, finding the expected pattern of differential memory bias only among Japanese, but not Italians. There was also an indication of selective language use corresponding to the age-based categorization. Study 2 replicated the age-based categorization among Japanese participants and provided visible evidence that the sensitivity in choosing appropriate language styles co-occur with memory bias. We discuss implications of these findings for understanding the complex interplay between culture, language, and social cognition.