A nudge is a behavioral economics technique that subtly encourages people to make optimal choices without forcing them through laws or other means. In 2011, a certain area of London was having a hard time with antisocial people vandalizing store windows, but when the store painted pictures of babies on the windows, vandalism drastically decreased. In Japan, where the declining birthrate is a major problem, it might be a good idea to use nudges to subtly encourage marriage and childbirth. Alternatively, nudges can be used to create a trend away from a concentrated concentration in Tokyo to regional decentralization. (Kei)