“If you whistle at night, snakes will come out!” is the first and one of the most curious superstitions on our list. There are two reasons for this nightly whistle ban – the first one is of supernatural nature and lies in the fear that a monster might be drawn out by the whistling. The second reason is based in reality, and “snakes” is actually an idiom for people of the shadier sort. It is said that in old Japan, human traffickers, thieves, and other criminals used whistle sounds to communicate with each other at night. A careless whistle in the dark might get you an unwanted visit by either a monster or a hoodlum, so be warned.

This superstition has to do with the Japanese name for thumb: oya yubi, literally “parent finger.” Thus, by hiding your thumbs in your palm when you see a hearse, a very prominent symbol of death, you protect your parents from an untimely passing.
Another version of this eerie superstition states that the spirits of the dead cling to a hearse and they might enter your body by slipping underneath the fingernails of your thumbs.

Undoubtedly one of the most curious superstitions, this one states that “when you cut your nails at night, you will not be able to be there for the death of your parents” – because you’ll die before them. The expression for “cutting nails at night” sounds unpleasantly similar to “shortening one’s life,” with both being read “yozume.”
Another, more practical explanation is that in old Japan, people used knives to cut their nails. This can quickly turn into a fatal accident in the dark night!

“If you lie down right after a meal, you’ll turn into a cow!” While this superstition is obviously not true, it is still a phrase jokingly spoken to children after a meal to children. It is believed that this phrase mainly exists to discourage laziness from a young age.

“Let spiders live in the morning, kill spiders at night” is a popular Japanese superstition stating that seeing a spider in the morning brings good luck while such an occurrence brings bad luck at night. One theory is that the spider’s morning visit symbolizes a guest during the day, while the nightly encounter symbolizes a thief.

Hearing a crow’s cawing can mean multiple bad things, for someone dying right now to illness and accidents, and even a large earthquake occurring soon. This superstition is closely connected to Japanese mythology, in which a large crow called Yatagarasu acts as a divine messenger and symbolizes the deities’ will to intervene in human affairs.

One of the most widespread superstitions is to not sleep with your pillow facing north. This belief has its roots in Buddhist funeral practices, in which the deceased are laid down with their head facing north. Doing so in your sleep is said to shorten your life.

“Hide your belly button during a thunderstorm!” is a phrase that many Japanese people might remember hearing as children. This superstition has to do with the Japanese deity of thunder, Raijin. He is the one causing the thunder in a storm and is said to have a particular passion for children’s bellybuttons – if one is exposed, he might swoop down and devour the tasty little treat.

Much like it is supposed to bring bad luck when you break a mirror in Western cultures, Japan has a similar superstition but swaps the mirror for a comb and its teeth. This belief comes from myths about the deity Izanagi no Mikoto, who used his comb to uncover a rather nasty deception and to help him escape from pursuers, throwing it to the ground where it grew into bamboo shoots. So don’t ruin your comb, it could be a life-saver.

Much like with the hearse, people say that you shouldn’t leave your wet clothes to hang out to dry overnight is because of the lingering spirits of the dead. It is believed that those spirits cling to the deceased’s possessions – and in a time of kimono being passed down through generations, no one wants a surprise visit by great-grandmother’s ghost.