Japanese superstitions are rooted in the culture and history of Japan and the Japanese people. Superstitious beliefs are common in Japan; most have roots in Japan's history. A number of Japanese superstitions have their basis in Japanese custom and culture and are meant to teach lessons or serve as practical advice.
Some superstitions that are common in Japan have been imported from other cultures. The unluckiness of a black cat crossing one's path is one notable example. The Japanese also share superstitions with other Asian cultures, particularly the Chinese, with whom they share significant historical and cultural ties. The unluckiness of the number four is one such example, as the Japanese word for "four" sounds like the word for "death."
A significant portion of Japanese superstition is related to language. Numbers and objects which have names that are homophones for words such as "death" and "suffering" are typically considered unlucky. Other superstitions relate to the literal meanings of words. Another significant part of Japanese superstition has its roots in ancient Japan's ancient Pagan, animist culture and regards living and natural things as having certain powers or spirits. Thus, many Japanese superstitions involve beliefs about animals and depictions of animals bringing about good or bad fortune.
Folk wisdom 
- If you play with fire, you will wet your bed. (It makes children become aware of the danger of fire.)
- If you rest just after eating, you will become a cow/pig/elephant. (This means not to be lazy.)
- If you whistle or play a flute at night, snakes will come to you. (This means not to bother your neighbors.) (When they say snake, it means a thief.)
- A cold midsection will cause diarrhea
- The first dream of a new year will come true
- Breaking a comb or the cloth strap of a "geta" wooden sandal is an omen of misfortune.
- Stepping on the cloth border of a tatami mat brings bad luck.
Linguistic superstition 
- If a funeral hearse drives past, you must hide your thumb in a fist. This is because the Japanese word for thumb literally translates as "parent-finger" and hiding it is considered protection for your parent. If you don't, your parent will die.
There are several unlucky numbers in Japanese. Traditionally, 4 and 9 are unlucky. Four is sometimes pronounced shi, which is also the word for death. Nine is also sometimes pronounced ku, which can mean suffering. 13 is also occasionally thought of as unlucky, although this is imported from Western culture. Because of these unlucky numbers, sometimes levels or rooms with 4 or 9 in them don't exist in hospitals or hotels, and particularly in the maternity section of a hospital, the room number 43 is avoided because it can literally mean "still birth". Therefore, when giving gifts such as sets of plates, they are normally sets of three or five, never four.
Death and the supernatural 
- If you go to a funeral, you should throw salt over yourself before entering your home. This is believed to be cleansing.
- You should never sleep with your head in North position or you will have a short life (this is the way a body is laid out at funeral).
- Chopsticks should not be stuck upright into food, especially rice. Chopsticks are only stuck upright into rice in the bowl on the altar at a funeral.
- Food should never be passed chopstick-to-chopstick as this is done in a ceremony where bone fragments from cremated remains are placed in an urn. This is called "hotokebashi".
- Cutting your fingernails or toenails at night is bad luck. If you do so, it is believed that you will not be with your parents at their deathbed.
- You should never write a person's name in red ink. This is due to names on graves being red.
- Use of the Maneki Neko or "lucky cat". Many businesses such as shops or restaurants have figures of such beckoning cats. These are considered to be lucky and bring in money and fortune.
- If you see a spider in the morning, it means good luck so you shouldn't kill it, but if you see one at night, it means bad luck so you can kill it.
- If you catch a crow's eyes, something bad will happen.
- If a black cat crosses your path, something bad will happen. (This is actually imported from Western culture.)
See also 
- Simon, Gwladys Hughes (July–September 1952). "Some Japanese Beliefs and Home Remedies". The Journal of American Folklore 65 (257): 281–293. doi:10.2307/537081. JSTOR 537081.
- "Japanese Superstitions Part 1 - Death and the Number 4". Japan Zone. Retrieved August 14, 2012.
- "Japanese Superstitions, Part 2 - Omens and Floor Plans". Japan Zone. Retrieved August 14, 2012.
- "Japanese Superstition". Japan Guide. Retrieved August 14, 2012.
- Shuji, Matsushita (September 30, 2007). "A mouse in cat's skin". CNet Asia. Archived from the original on June 3, 2008. Retrieved August 14, 2012.