Those originating from Tokyo/Yokohama: return Shinkansen fare.
All seasons: sturdy, comfortable shoes or boots with good grip, suitable for 3km forest walk.
Winter, we may encounter snow: warm coat, wollen hat, gloves, rain parker (or umbrellas provided)
Summer: sun hat, sun glasses, sunblock, water bottle, rain parker (or umbrellas provided)
Spring & Autumn: Winter or summer gear as above depending on weather of the day