Itto-seki, literally meaning 'one-sword cut', is a massive split boulder located in the picturesque Yagyu countryside. Legend attributes the split to the legendary swordsman Yagyu Muneyoshi (also known as Sekishūsai), who sliced the rock in one swift stroke during his training. The mysterious boulder has become a popular pilgrimage site, especially for fans of the anime and manga series 'Demon Slayer' (Kimetsu no Yaiba), due to a similar scene involving a split rock. Visitors can admire the impressive size and clean split of the Itto-seki, and immerse themselves in the local legends surrounding this historical landmark. Visit Amenoiwatate Jinja on your way to the boulder.