22-Sep-2018 -- I planned a two-day visit to Osaka to do two things: pick up a brand new iPhone XS on its launch day, and visit a nearby confluence point. With the first objective successful, I made my way to the second objective the day after. From the Osaka station, I took a train that went to Himeji and got off at Kakogawa. From there, I transferred to a train that travelled northward and arrived at Nishiwakishi. Another transfer and I ended up at the Nihon-heso-kōen station. This took about two and a half hours from the Osaka station.
As other visitors have already noted, Nihon (Japan) heso (navel) kōen (park) is so named because the confluence point 35N 135E is considered the navel of Japan and the locals have decided to build a park around it several decades ago. It's pretty rare to see a confluence point that has its own train station, but there you go.
Going past the park's welcome sign that has an explainer of the location's significance in Japanese, I was soon able to arrive at the base of the monument that marked the point. You can access the center (and thus the actual point) via a small zigzagging path that went up the hill, eastward. My iPhone showed that the exact coordinates were around 2 meters from the monument base. I forgot to bring a second phone to take this picture, but luckily, a passerby let me borrow his phone and I was able to take it. Many thanks to the guy. From here, I was able to see the Nishiwaki Latitude-Longitude Earth Science Museum - Terra-Dome towards the west(photo #5, photo #7). The views of the other directions were mostly dominated by the hill and the trees (photo #2, photo #3, photo #4).
With the visit complete, I went back to Nishiwakishi station by foot to return instead of going to Nihon-heso-kōen station due to the sparse train schedule.