Battle of Uedahara
1548 CE.
Shown on the map at 36.396°, 138.213°.
The Battle of Uedahara (上田原の戦い) was the first defeat suffered by Takeda Shingen, and the first field battle in Japan in which firearms were used. It took place in Shinano Province or the modern-day Nagano Prefecture.
Text from the Wikipedia article Battle of Uedahara, licensed CC BY-SA 4.0.