Yami to Hikari no Sanctuary

Souji, trained in his family's secret martial arts discipline for combating supernatural threats, arrives at the remote island of Niizajima as bodyguard to Arisu, a wealthy heiress searching for her missing older sister. The academy where Arisu enrolls teems with cryptic local customs that seem designed to conceal something sinister beneath the surface. Joined by a growing circle of allies—including childhood friend Yuuri, corporate rival Claudette, and an enigmatic classmate named Julie—the group begins unraveling the island's mysteries through investigation and careful planning. Their quest for answers about Arisu's sister leads them to discover far more than they bargained for: a throng of malevolent spirits haunting Niizajima, drawn from the very legends and folklore whispered throughout the community.