Do a lot of people on this board watch Japanese cartoons (normal or porn variety)?
Speaking as to people who actually live here:
The largest percentage back in the day when I came here were the Zainichi Koreans, who made up 75% of the foreign population, and diaspora Chinese made up another 12%. Most of these were multi-generational families who'd lived in Japan since before the war. There were also a pretty sizeable chunk of Brazilians, Filipinos, and Peruvians coming in for economic reasons, usually under descendent visas.
Pre-Internet, most of the Western foreign arrivals in Japan were here for martial arts, religion/philosophy study, culinary, linguistics, motorsports, architecture, or a work transfer. Largest number were the military people.
Post-Internet, there's a marked increase in people coming here specifically for Japanese pop culture, fashion, geek culture, and yes, even some who are here just for porn and P4P.
Tourists vary a lot, but the bulk of them recently seem to be here for "wacky Japan".
I still wish that all the tourists had a single neck for me to wrap my hands around....