Sakuya Outsuki is a high school student and the son of Tatsuya Outsuki, a world-renowned detective famous for solving even the most difficult cases. Sakuya has inherited his father’s most unusual trait: the ability to return to life after being killed. Despite this useful power, he is nothing like his thrill-seeking father. Sakuya remembers every detail of each death he experiences, making the process genuinely traumatic, so he prefers to focus on mundane and low-risk cases like investigating infidelity or finding lost pets.

Sakuya is assisted by Lilithea, a sharp and observant 16-year-old girl who acts as his partner. While she is dutiful and capable in her work, she has a quirky and sometimes robotic demeanor, often criticizing Sakuya for his lack of ambition. The story begins when his father departs for Singapore to investigate a major airplane hijacking, leaving Sakuya and Lilithea to handle their own affairs. They take on what seems like a simple assignment: following a famous movie producer to gather evidence of an affair. This investigation leads them to board a luxury cruise ship.

While on the ship, Sakuya and Lilithea are asked to find a missing cat named Lulu, which belongs to the person they are already following. Their routine case takes a dark turn when Sakuya discovers the body of a murdered man. His investigation puts him in grave danger, and he is killed once again. However, he soon reopens his eyes with Lilithea by his side, ready to use the clues he gathered before his death to solve the mystery. The central narrative follows Sakuya as he is forced to confront his own mortality repeatedly, balancing his desire for a safe life with the reality that dangerous cases often find him. The series blends classic detective fiction elements with supernatural fantasy, focusing on Sakuya’s personal struggle with the trauma of dying and his quest to live up to his father’s legacy.