About halfway between Tokyo and Nagano.
Here's what it looks like in the daytime:
Here's the plaque explaining it, and the cherry blossoms(?)
Can anyone translate the plaque? Japanese OCR seems to be hopeless...
As featured in anime TV series Yuru Camp S3, episode 10
In the episode, they also mention the Usui Pass Railway Heritage Park where you can actually drive their working EF63 electric locomotive!