After losing his parents, Shinpei Ajiro resided with the Kofune sisters, Mio and Ushio, until moving to Tokyo solo. Tragedy strikes when Ushio perishes while rescuing Shiori Kobayakawa, prompting Shinpei's return to unravel the mystery. Suspecting foul play due to bruises on Ushio's neck, he delves into a world of sinister forces lurking within the community. A ghostly message from Ushio urges him to 'protect Mio,' setting off a chain of revelations. Guided by Mio and allies, Shinpei fights to secure a safe future amidst escalating threats. However, each inquiry uncovers more despair, engulfing their island in shadows. As he grapples with mounting challenges, Shinpei must endure further anguish to unearth a path to salvation for all.