Densetsu: a hidden realm existing alongside ours, veiled by a mystical border. Within this utopia, humans coexist harmoniously with fairies, monsters, and even gods. Nestled in the lofty mountains, the Kamiyama Shrine Maiden guards the border, transforming her shrine into a gathering place for residents from across Densetsu. Feared by monsters yet adored by humans, she maintains the delicate balance. Enter Kotaro Nishiki, a senior at Islander High School, who stumbles upon a fork on the road, transporting him into Densetsu. Here, he forges friendships with non-humans and becomes entangled in the realm's myriad issues. His initial challenge: resolving the notorious Infinite Loop incident, a relentless cycle triggered by Kotaro's demise. As his journey unfolds, he delves deeper into the secrets of Densetsu, seeking to unravel the mysteries that lie within.
''The Sannin (伝説の三忍, Densetsu no Sannin, literally meaning: Legendary Three Ninja) were three renowned ninja from Konohagakure, hailed as the greatest of their time.''