In Isle of Fall, Satoshi and Mary, a couple looking to revive their fading spark, travel to a remote island after receiving a strange invitation from Satoshi's uncle. The island is home to a mysterious autumn ritual said to eternally bind couples who prove their love through a challenging experience held in a secluded, abandoned mansion. Joined by their friend Hanako and fellow couple Natsuki and Yoshi, the group anticipates a playful Halloween getaway filled with costumes and romance. But soon after arriving, Satoshi notices something is wrong. The eerie atmosphere of the old mansion, combined with the strange behavior of the event's hosts, creates a growing sense of unease. As unsettling events begin to unfold in the mansion's secret corners, it becomes clear that their romantic trip may have more disturbing intentions hidden beneath it. What started as a fun escape could become a night none of them will forget for reasons they never imagined. This game contains UNAVOIDABLE NTR.