This work explores the development and applicability of core theories in cultural psychology, focusing on Brazil and Japan. It analyses systems of thought (holistic vs. analytic cognition), emotional frameworks (ideal affect, happiness), cultural logics (dignity, face, honour), relational mobility, monumentalism/flexibility, tightness/looseness, individualism/collectivism, and self-construal (independent/interdependent). Brazil and Japan display pronounced contrasts in certain domains, yet unexpected parallels in others. This work stresses the necessity of diversifying psychological research to encompass non-US or Western European perspectives, fostering a more globally representative understanding of human behaviour.