In Japanese culture, certain numbers are considered lucky while others are believed to be unlucky. The number 7 is the luckiest number in Japan due to the seven gods of fortune in Japanese mythology, while the number 4 is avoided at all costs because it sounds like the word for "death" in Japanese. Lucky numbers play a significant role in everyday life, including business, weddings, and even soup on New Year's Day. Understanding the significance of these numbers is crucial for anyone doing business or celebrating events in Japan.