I only lived in Tokyo for a few months, but I felt like there was a lingering loneliness paradoxically exacerbated by the high population density. Growing up around Southern hospitality set a high bar, but even compared to less friendly parts of the States, it was hard to strike up random conversations that were deeper than anything superficial. It's a hard culture to break into if you're obviously a foreigner because of the high language barrier, and you start seeing the same faces in the expat circles after a while. Still a great city where I made a lot of deep connections, and I wouldn't pass up an opportunity to park myself there for a few years.