Mushi to Medama Series

Sakaki Guryuu is a multi-talented genius who, despite being gifted and wealthy, chooses to leave his privileged life behind to teach in the countryside. There, he finds himself drawn to Usagawa Rinne, one of his students, and their relationship develops into something deeper than teacher and pupil. However, their idyllic rural existence takes a dark turn when a mysterious girl named Gankyuu Eguriko appears, bringing with her unsettling violence and cryptic references to something called "Eden's Apple." As the peaceful world Sakaki and Rinne have built begins to unravel, they find themselves caught up in events that challenge their understanding of reality itself.