The laws about smoking are different in Japan. In America, smoking is barred from most establishments, but it's fine to smoke pretty much anywhere outside as long as it's far from an entrance to a building... Which is a rule that isn't always followed.
In Japan, a lot of bars and restaurants allow smoking, but it's actually against the law to smoke outside except for in designated areas. The thought process behind this is that if you're in a bar and someone's smoking, and you don't like it, you're choosing to be in that bar. You don't really CHOOSE to be outside; everyone has to go outside at some point, and if someone's smoking, there's no real escape for it.
I find some smokers disgusting, but the act itself isn't always so. In my case, for instance, I have asthma, and when I'm at a bar, I find smoking extremely light, menthol cigarettes opens my lungs a bit so the second-hand smoke isn't bad. I've always reacted far worse to second-hand smoke. If smokers are polite, as in, putting their arm away from people they're smoking around, ashing their cigarette often enough to not get dust everywhere, and ESPECIALLY taking care to blow smoke away from people, especially people they're talking to? Those people are fine.
It's the people who smoke around people who don't smoke, and then get offended when they cough... Those people make me angry. Same goes for the people who throw still-smoldering butts into the grass, or onto the sidewalk, or out their car window.
Smoking in general doesn't bother me, all health issues aside. Smokers, however, have a tendency to look out only for themselves, and they make the habit way more disgusting than it needs to be.