Possibly related to this question about carrying passports everywhere.
In preparation for my first trip to Japan, I have my UK passport, which is of course kept on hand at all times when I'm travelling. If the police or airport staff in Japan ask for identification, it is what I will use. However, if I were ID'd in a bar or supermarket for - as an example - buying alcohol, I would think it unlikely the staff could recognise a genuine foreign passport.
I was curious to know if foreign passports (or other forms of ID such as drivers licences) are indeed acceptable in Japan, or is there some kind of travellers ID that can be obtained prior to my visit?