The Gion Festival
Fan Concept Art for what an Assassin's creed set in Japan during 1600-1800 could look like, I would probably call it Assassin's Creed Ikigai but I imagine they would call it something like "Rise". I know that the low height of the buildings is one of the things that has kept Ubisoft away from old Japan, but a lot of the buildings had two heights even if most were 1-2 stories, which could make for some great parkour.
I wanted to show an example mission that would fit well within the game and would tackle that height issue right in the heart of the city, The Gion Festival. Named after the redlight district in Kyoto this was a set of floats that would and still go around Kyoto in the summer, back then Shijo Street displayed here would of been much more narrow than it is today, I read about 10 feet. While a lot of the buildings back then just had wood with rock supports as roofing, the main streets usually had tiled roofs. The mission could play out having to go float to float to find the target, you could have a variety of shapes for the floats from towers to boats to make climbing more interesting.
I did this for practice/example of working within an established IP and for concepting historical games/films. I went to museums around Kyoto back when I lived there for a few months and rented out a few Library books here as a reference. It was actually a lot of fun.