Beppu, Japan

With a population of just 125,385, Beppu may seem like a quaint onsen town, but the reality is a dense urban area with significant challenges. The city's infrastructure is clearly straining to keep up - the narrow alluvial plain leaves little room for expansion, while the mountainous terrain creates logistical headaches. And let's not forget the ever-present volcanic activity and seismic faults, which make Beppu's bureaucracy a persistent headache for residents.

Still, the city's famous hot springs remain a major draw, attracting tourists year-round. But for those seeking a slower pace of life, Beppu may prove too crowded and high-maintenance. This is a city best suited for die-hard onsen enthusiasts and those who can navigate its quirks.