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Some superstitions that are common in Japan have been imported from other cultures. The Japanese 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". However, unlike most other countries, in Japan, a black cat crossing one's path is considered to bring good luck.
A significant portion of Japanese superstition is related to language. Numbers and objects that 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 Japan's ancient pagan, animist culture and regards certain natural things as having kami. Thus, many Japanese superstitions involve beliefs about animals and depictions of animals bringing about good or bad fortune.
- Resting just after eating results in becoming a cow/pig/elephant. (This discourages laziness.)
- If whistling or playing a flute at night, snakes will come out. (This means not to bother the neighbors.) In this context, "snake" means a thief.
- A cold midsection will cause diarrhea.
- The first dream of a Japanese 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.
If a funeral hearse drives past, one must hide one's thumbs in a fist. The Japanese word for "thumb" literally translates as "parent-finger". Hiding it is considered protection for one's parents. If this is not done, one's parents will die.
7, when pronounced "shichi", sounds similar to the number four (四 shi). It is considered a good number since 7 symbolizes "togetherness". 8 is considered a lucky number because it is nearly homophonous to the word "prosperity" (繁栄 han'ei), It is also homophonous to Hachikō. 9 is considered a good number when pronounced "kyū", like a word for relief. 10 is considered a good number because it is pronounced "jū", like the word for "enough" and "replete". It is also a homophone for the word "ample" (十分な jūbun'na).
There are six unlucky numbers in Japanese. Traditionally, 4 is unlucky because it is sometimes pronounced shi, which is the word for death. Sometimes levels or rooms with 4 don't exist in hospitals or hotels. Particularly in the maternity section of a hospital, the room number 43 is avoided because it can literally mean "stillbirth". (死産 - shizan: 死 - death/to die and 産 - childbirth/produce). In cars and racing, number 42 which sounds like shini (死に – to death) and 49, which sounds like shiku (敷く – to run over) are avoided. When giving gifts such as plates, they are normally in sets of three or five, never four.
Number 9 is sometimes pronounced ku — with the same pronunciation as agony or torture. Combs (kushi) are rarely given as presents as the name is pronounced the same as 9 4.
Due to these unlucky connotations, the numbers 4 and 9 are often pronounced yon and kyuu instead.
The number 13 is occasionally thought of as unlucky, although this is imported from Western culture.
Death and the supernatural
- After a Japanese funeral, the mourners perform a cleansing ritual by throwing salt over themselves or scattering it on walkways leading to the front door. 
- Sleeping with head to the north results in 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 or when paying respects to the deceased. This is called hotokebashi.
- Food should never be passed chopstick-to-chopstick, this is done only in a ceremony where bone fragments from cremated remains are placed in an urn.
- Cutting fingernails or toenails at night is bad luck. If one does so, it is believed that will not be with parents at their deathbed.
- A person's name should not be written in red ink. (This is due to names on grave markers being red.) 
- Use of the Maneki Neko or "lucky cat". Many businesses such as shops or restaurants have figures of such beckoning cats, which are considered to be lucky and to bring in money and fortune.
- A spider seen in the morning means good luck so the spider should not be killed. If a spider is seen at night means bad luck so it should be killed.
- A crow's caw means something bad will happen. This can be anything from illness or accidents to death or natural disasters. 
- Ehou-maki are eaten during Setsubun in a lucky direction.
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