Japan is the only country with a law requiring married couples to share the same surname, with 95% of women adopting their husband's name. Changing the law is challenging, especially with 90% of lawmakers being men. Asuniwa, a leading gender equality organization, partnered with Tohoku University’s professor to project the law's future impact, concluding that by 2531, "Sato" would be the only surviving surname in Japan. To spark conversation, 40 entities—companies, artists, manga characters, and athletes—renamed themselves "SATO." Armed with this data, Asuniwa shared the findings with UN Women, leading to a recommendation for Japan to revise the law within two years. A candidate advocating for change was then elected prime minister.