Eternal Life Plan

People who I once clearly remembered were dead have been contacting me one after another recently and are still alive and well. Is this a well-planned prank? Or is there serious confusion in the brain's memory? I couldn't sleep or eat well, so I decided to find out. After clearing away layers of fog, it was discovered that it was inextricably linked to an operation, a murder, a plan, a school beauty, a genius, and a conspiracy six years ago...