Kaga Spa Trail 100K is a mountain trail race in Kaga City, Ishikawa Prefecture, centered on Yamanaka Onsen and run in June as part of Kaga Spa Endurance Trail by UTMB. The long race starts in the hot spring town in the evening and returns there after roughly 95 to 97 km of running, with about 5,100 m of climbing and a 27-hour limit. It is a UTMB World Series 100K event, so finishers earn 3 Running Stones, and the strongest men and women can earn direct entry rights toward the UTMB Final CCC. The field is for adults, but the format includes front runners aiming for an estimated 11-and-a-half-hour finish and runners using nearly the full time limit.
The course mixes single track, scree, streams, forest roads, steep climbs through beech forest, and technical descents over roots and loose ground. A drop bag is available around 63.6 km, and the LUC+ support package adds tour aid support near the same point for runners who are not joining an accommodation tour. The finish has a local hook: runners come back through the old onsen town and head for Yamanaka Onsen's public bath, Kikunoyu. After the race, they can soak in hot spring water tied to roughly 1,300 years of history, which makes the ending feel less like a standard finish chute and more like a return to the town that hosts the race.