Killed Again, Mr. Detective?

また殺されてしまったのですね、探偵様

Every investigation Sakuya Otsuki takes on ends the same way: he dies. The high school son of a legendary detective, Sakuya keeps waking up after each murder to finish the case with his assistant Lilithea, who has learned to expect the worst and start solving anyway. Hired to look into a film producer's affair aboard a luxury cruise ship, he is dead again long before the job stays that small, but a body with no pulse has never stopped him from working a scene.