板室温泉スパトレイル16K & 48K 2026

The Itamuro Onsen Spa Trail 16K & 48K begins and ends at Numahara Marsh Parking Area in Nasu Shiobara, Tochigi Prefecture, situated on the back side of the Nasu mountain range. This trail-running event takes place in July and offers two distances: a 16K race completed in one lap and a 48K race completed in three laps. The 48K distance can be run solo or as a relay. The course follows a 16 km loop in the Ura-Nasu area, run counter-clockwise, with 625 m of elevation gain per lap. This setup accommodates various runners: one lap for those seeking a shorter mountain race, three laps for solo ultrarunners, and a team option for groups. STRIDE LAB organizes the event, participants receive gifts, and past reviews indicate teams return annually to run together.