Hey there!
Honestly, that's mainly due to availability of assets in the software I use. A lot of the assets are Japanese in some way or another, so going with that made sense at the time. (I didn't know what I know now about texture editing etc.)
Besides that, a Japanese setting appeals to a lot of people and is certainly more "interesting" than boring ol' Germany. Not to mention that I can't see myself making the characters visit an Oktoberfest or something lol
Thanks! Glad you enjoyed the update!