Final answer:
The statement about the Japanese being reluctant to express emotions in public is true, reflecting a cultural norm valuing group harmony and impacting the country's subjective well-being index.
Step-by-step explanation:
The Japanese indeed tend to be reluctant to express emotions in public. This is a part of Japanese culture where public display of emotion is often subdued as a sign of respect for the harmony of the group and to maintain social order. This cultural norm can impact various aspects of life in Japan, leading to a low subjective well-being index, despite the country's considerable wealth.
The concept of subjective well-being entails the personal assessment of one's life satisfaction and emotional experiences. Hence, while Japan may have higher economic wealth compared to some countries like Ireland, it does not necessarily equate to an overall sense of happiness or satisfaction among its citizens.