It’s fun to analyze Japanese culture through its superstitions, which are plentiful here. Don’t cut your fingernails at night or you won’t be able to be with your parents when they die. Never write the name of a person in red ink or they will die. If a stalk of green tea stands upright in your cup, you’ll die…actually no, you’ll have good luck. Many superstitions are directly die to death and funerals, for example, never sleep with your head pointing north (北枕 kita-makura), as dead bodies are laid out with their heads pointing in this direction on the night before a funeral. Quite a few Japanese superstitions seem to be tied to the way a certain word is pronounced, for example Japanese avoid the number four because it can be pronounced shi which happens to also mean “death.” There are “unlucky years” in a person’s life, called 厄年 yaku-doshi, which are age 42 for men and age 33 for women…but these ages seem to have been selected because “42” sounds like shini (also meaning “death”), while 33 can be read san-zan (meaning “many difficulties and troubles,” as with childbirth). The word ご縁 go-en means relationship, connection or a lucky chance meeting, and since this is also how you say “five yen,” the 5 yen coin (the really cool one that looks like gold, with the hole in the center) is considered a lucky coin that will help you form important relationships. (Japanese omamori good luck charms often have 5 yen coins inside them, like this one.)
Some random information on Japanese culture for you.