A local islander kindly drove me here, but I think it probably wouldn't be easy even on an electric-assist bicycle. There were spider webs too, and it felt like nobody had been in for a while. You go down from the animal trail(?) that loops all the way around, but it might be hard to figure out unless you go with someone who knows the place! Koshiki no Ana is a volcanic crater formed by an eruption in the 1600s. After hundreds of years, grass and trees have grown in thickly, and you can't really sense much of what it once looked like.

Near my work site there was a sign saying "Koshiki no Ana Trail, 15 minutes to the summit," so I tried walking it during my break. Along the way there were fallen trees, and lots of fallen trees with branches growing upward from them. At first it was wide enough to walk side by side, but it gradually got narrower and steeper. Partway it split left and right, so I chose the path that went up. Then it suddenly opened up, and this seemed to be the summit. There was a summit sign, but it was pretty decayed. I searched around for where the hole was, but couldn't find any hole. Since I didn't get it, I looked it up, and apparently it's the remains of an old crater. There's an open area where that spot is sunken, and it apparently resembles a koshiki (an old earthenware vessel), so it's called Koshiki no Ana. I thought "Oh, that's it?" and was about to head back, but since I'd come all this way, I went to see it. Taking the downhill way at the fork from earlier, there was a path going down, so I went down it. It was quite steep and wound down left and right. Then gradually the open area came into view. When I got down, it was big enough to play a pickup baseball game. But since not many people come, it was pretty neglected. It really struck me that depopulation is progressing here too.

A crater from the 1643 eruption. However, the entrance might be hard to find. Once you finish climbing the steep slope, the former crater forms a hollow that has now become a grassy field. Around the outer rim there's a walking path like an animal trail, and there's also a summit with a good view. Apparently all of it is maintained by forest-building volunteers. Overall, you can see everything in about an hour. There's also a path on the side opposite the trailhead, but it's a somewhat rugged, steep slope.