Going to a hospital or clinic is always quite nervewracking, even more so if it's in a foreign language and country!
So here are the very basic things to know if you have to visit the doctor in Japan. Bring your ID card, the best is usually to use your Foreign Registraiton card (aka 在留カード、ざいりゅうカード) and your insurance card, usually one from your ward/city office (国民保健、こくみんほけん) or one provded by your company etc.