Older Sister’s Day, also known as Ane no Hi or Big Sister’s Day, is observed worldwide every December 6. This informal holiday was created by Japanese manga artist Kunio Hatada to celebrate the role of older sisters in the lives of their siblings. The holiday originated in the early 1990s when Hatada, while researching sibling relationships, initially proposed Younger Sister’s Day for September 6, associating it with the Virgo astrological sign. He later expanded this idea to include Older Sister’s Day, which is celebrated three months later. Although it is less popular than Younger Sister’s Day, it is primarily recognized by manga and anime fans who honor iconic older sisters from their favorite stories. Celebrations may include giving gifts, dining out, or sharing fond sibling memories on social media using hashtags like #OlderSistersDay and #BigSistersDay.