Not to criticize you but most Japanese people outside manufacturing are extremely slow & inefficient at work. At least from a western perspective. But the thing is Japanese society doesn't really differentiate between work and "real life" in the way the West does. I work to get paid, not for any shakai purpose. Part of why I keep getting consulting work is I do much more in the same time than company staff can ever do even with them staying late.
EDIT: Also from what I've seen most of that "5PM urgent" stuff can be put off a day. I tell people that they should have thought of it earlier and that they should be more ishokeme about thinking of scheduling.
Most of them aren't getting OT pay. HR will classify many people as "managers" because management can't get OT pay. I used to drink with an HR manager who told me he even classified his cleaning grew as managers for that reason.