Why is the south of japan often called the west (and the north called the east) in sengoku era japan?
for example:
the armies of Mitsunari and Ieyasu being called western and eastern.
Tachibana Munetora being called " the great warrior of the west" despite being located in Kyushu.
Takeda Shingens procession to the Kyoto being described as westward.
many references to Hokkaido and Kyushu as being western or eastern.
It's important to remember that Hokkaido wasn't under Japan's control at the time. What is now North East Honshu was back then sort of the frontier and very sparsely populated (it's still sparsely populated but anyways). Take out those two regions, and Japan really is very much west to east, rather than southwest to northeast.
Adding to the confusion is that mapping technology just wasn't very good back then. And the northeast being deserted certainly didn't help. Take a look at these old maps of Japan:
https://upload.wikimedia.org/wikipedia/commons/thumb/4/47/Gyokizu.jpg/1280px-Gyokizu.jpg
So the evidence point to that simply that the Japanese really thought they were west and east. More accurate maps of the archipelago did not start appearing until the closing days of the Sengoku via the Jesuits, and when lords and governments started going around trying to make and collect accurate maps for administrative purposes.
By the way, for Takeda Shingen to go from his home of Kofu to Kyoto is in fact travelling westward.
