The subway rumbled toward its final stop north of Seoul. Along the way, hordes disembarked, with the determined, brisk gait of those with somewhere to be.

Far from the city center, the thicket of high-rise buildings grew sparser, and the afternoon sun crept deeper into the train cars, riding on an elevated track at that point. By the end of the line, many who remained on board were noticeably older — nodding off, gazing out the window, stretching their shoulders.

Lee Jin-ho — dressed smartly in a straw hat, white Adidas and a crisp hanbok — had taken two subway lines for more than an hour from his home to the last stop, Soyosan, on a steamy August day. He ambled about 100 yards beyond the station, rested briefly in the shade — and then got right back on the train heading south.