What are some key differences between Medieval Europe and Feudal Japan?

Hello, I just joined today, I wanted to ask something related to a story I’m writing (any posts I may make showcasing the actual chapters will have the nsfw tag since the story’s violence and language in particular are more geared towards adult readers). I don’t want to get into too many details in this first post about my setting (the basic premise is that it’s a setting that takes place in a fantasy RPG world, since the idea was originally a hypothetical game idea I thought of roughly a decade ago when I was in sophomore year of high school), purely for the sake of being brief, but like most fantasy settings I’ve come across, this one is based mainly off of Medieval Europe (particularly in this prologue story I’m currently working on). I’m drafting a location during this prologue’s era based off of Feudal Japan (the idea mainly came to me as a need to have an in-universe reason why one of the main characters of this story wields a katana, a “maybe I should do this” idea that just grew from there), and since I trust the judgement of you all better than my own (I assume you all generally have more experience with larger writing projects than I do, since this setting is my first), I was wondering if anyone could give me some key differences I can use to better write this location. I’m mainly looking for key differences because I want to write this location with respect to Japanese culture, and I think looking at key differences would be the best place to start for striking a balance, since I don’t want to oversimplify their culture but also want to avoid overly romanticizing it, since I feel like both extremes would be insulting, which is something I always try to avoid in my work when covering walks of life that aren’t my own. This may be unnecessary to ask now, since that location is planned for much later in the story (for context, I’m just getting around to writing the second chapter of this prologue after a massive art block), but I figured it would help to at least draft an idea now, so that I have a plan when the time comes to write it.