Japan did have a slavery system until it was abolished in 1590.
People swallowed the propaganda whole, believing that slavery is primarily--if not purely--a Western (this is a euphemism, BTW--only
one specific societal group of humanity is meant when "Western" is used) phenomenon.
They ignore the fact that slavery is a
human phenomenon--one common to all societies throughout all ages of human history--which occurred because of one simple fact: human nature is not pretty.
Without moral enlightenment, a human only cares about himself/herself, and will seek gratification to the detriment of his/her neighbor--but has the intellectual capacity to make it happen in various ways no animal can replicate. "The weak are meat the strong do eat" is the saying, and humans--whether in systems of slavery or not--will live by it without a single thought given to the pain of others so "eaten" as long as they have no moral development beyond their base human urges. Animalistic self-centeredness combined with human intellect creates opportunities for atrocities of the same kinds recorded throughout human history.
That being said, slavery in any setting is not a big deal: every element of slavery that makes it worthy of stigma is absent, when used in these settings; people just complain because they've been programmed to have a knee-jerk reaction to the concept of slavery. The funny thing about that is that the slavery and slavery-like conditions they hate so much still exists in this modern world--but in the places they've also been programmed to ignore (e.g., Africa, India). And in keeping with that programming, they'll never say a word about those places, always calling slavery a "Western" phenomenon.
