Shirtsureishimasu (しつれいします) <2>
Traditionally, the Japanese believe that you cannot go home before your boss. Simply it is rude for you to do so. However, if you dare to say, “Shitsureishimasu (しつれいします)” and take off, you can unless you signed the contract, which says that you will stay until you get your job done.
(Overtime, unless you get paid extra for the work, is not welcome.)
In this case, “Shitsureishimasu” means “I am sorry to DISTURB or BOTHER you by going home when you can’t.” Mostly, “Shitsureishimasu” follows the word, “Osakini,” which means “before you (go home).” Especially, it is your boss or your supervisor that is left behind working, rookies are abligated to say, “Shitsureishimasu” extremely politely (Otherwise, they are going to be bullied by them!?).
(People try not to work overtime because they don’t get paid enough.)
In this workplace situation, there is no chance that employees might have to say, “Shitsureishimashita (しつれいしました <past tense>)” except when they are to leave their company executive’s private office.