Suizenji Park is in Chuo-Ku, Kumanichi reminds us somewhat unhelpfully. More helpful was supplying the name of that miniature Fuji there: apparently, it is called a “tsukiyama” 「築山, つきやま」. The quakes had caused its slopes to slide a bit, and during restoration, curious people wondered what it contains, so they conducted an excavation of up to 50cm to determine soil types and sedimentation layers. What they found was a bit surprising: remnants of a cannon base used during the Seinan War in 1877.
The location makes sense. Kumamoto (Higo) was invaded from the south by Kagoshima (Satsuma), and in that floodplain between the two, the tsukiyama was likely the highest point.
On a related note, I attended an historical lecture recently at which an elderly gent spoke. Of course, he wasn’t alive during the Seinan war, but his father was. The family fled to Mashiki, and when they returned, they found that the Satsuma army had eaten their dog and had left the dog’s neck on a block outside the house as a warning, as was traditional at the time. Since then, he said, his clan has disliked Satsuma. Seeing a living connection to such distant history was impressive. - William