The slopes of Kumamoto Castle are termed “mushagaeshi” 「武者返し」as they were designed to deter invaders, which is kind of the point of a castle. A mathematical analysis of the physics is shown below. I don’t understand mathematics, but apparently it worked until someone (Satsuma!) discovered cannon.
Kumanichi reports that deconstruction of the current Shinkansen station has begun, with the new station slated to be complete next March featuring a mushagaeshi motif. The article notes that castle walls are visible in the background. - William