I ran/hiked the Osaka Diamond trail on Friday, 12 May 2023.
I started my run at Sekiya Station at 6:46 AM, and reached the north trailhead at 7:06 AM. The weather was great, around 12 degrees when I started, peaking at 26 degrees at around 2pm.
I carried my own water and did not resupply along the way. I had two soft flasks (one 500ml, one 250ml) of glucose solution (totalling about 1200 calories) and a 500ml bottle of water. A little extra water would be nice, but was what I had was tolerable. For those attempting this trail supported/self-supported, please note that the only water sources I saw were vending machines at the top of Mt. Yamato Katsuragi (~13km in) and at Ishi River crossing (~43km in). There are a couple more toilet stops along the way but none of them had potable water.
The trail was not particularly technical, and most of the climbing/descending was done on well-maintained wooden steps. I did this FKT in road running shoes (New Balance FuelCell Rebel V3), which worked well for me. Outside of the three big peaks (Yamato Katsuragi, Kongo, Iwawaki), there was little foot traffic. If I were to do this trip again, I would probably learn the names of the peaks along/around the trail in Kanji to make use of the signboards.
The navigation was relatively easy, following a pre-planned track on my Garmin 945 resulted in relatively few errors after getting used to the general trail structure of the area.
I reached Sefukuji temple at 2:45 PM, for a FKT time of 7h 38m 54s, and continued on, ending my run at Izumi-Chuo Station, a nice 10km descent from the FKT finish point.