i'll take a stab at this.
i've lived here in japan for 5 years and not as an english teacher.
first, you need to understand the kinds of people who come live here. people who are adamant about living here usually exhibit most if not all of these traits:
1. they think moving to japan will make them happy
2. they're usually white kids from small-mid sized towns
3. they tend to be low-skilled and unemployable back home
4. they are almost always 24-34 years old. they maybe worked a year and are now looking to run away from the reality of work, having realized that they've not amounted to shit and that they have to take responsibility for that
5. these types of people are always, without fail, fat, unloveable, unfuckable, lazy, narcissistic slobs
So, this undesireable, unskilled, lazy, usually loudmouth foreigner moves to japan. japan offers them two things immediately:
by (1) giving them a job as an english teacher and (2) making them an exotic face in the dating scene, japan offers them a chance to pretend like that are desired as workers when they're not, and desired as romantic partners when they're uninteresting, cringe as fuck internet kids.
then comes time. maybe it's 5 months, maybe a year or two, but time passes. and the shine wears off. and the reality of life here sets in. and they realize that they have no friends, are hated and disliked by their coworkers, and their life here reminds them of their life back home. they're still the same undesirable, unskilled, lazy, loud person and now they're half a world away from the comforts of mom and dad's basement or their studio apartment in Portland.
their expectation of what life was going to be like here is shattered. then they bitch about how bad it is.
other people (pic related) really just are trying to get away from black people.