Being Japanese must be so time consuming.

[leroux]

'There is an extremely complex etiquette surrounding bowing, including the length and depth of bow, and the appropriate response. For example, if the other person maintains his or her bow for longer than expected (generally about two or three seconds), it is polite to bow again, upon which one may receive another bow in return, often leading to an exchange of progressively lighter bows.' [From Wikipedia's Bowing article]