In Japanese superstition, the number 4 is considered unlucky because its reading can sound like “death.” The number is commonly pronounced yon or shi, and shi is also the Japanese reading associated with death, written 死.
This association is an example of tetraphobia, the fear or avoidance of the number four. It is especially noticeable in hospitals, hotels, and other buildings, where a fourth floor, room 4, or room 44 may be omitted or labeled differently. The practice is not universal, and yon is often preferred in ordinary speech to avoid the unfortunate association.
The same sound-based superstition appears elsewhere in East Asia, although the exact pronunciation and strength of the taboo vary by language. Japanese number symbolism also has a contrasting lucky number: 7 is commonly associated with good fortune, including the traditional festival Shichi-Go-San.