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.
When you are nervous, write “human beings” ( “ningen” 人間 ) in Japanese on your palm three times and pretend to swallow them. It will help you to relax.