Ooe: Ariake-hen

A memorial service for the second anniversary of the actress Ann Ooe's death is being held on Ooejima, a remote island even further from Tokyo than Hachijo-jima. Our protagonist, Osaki, is employed by a detective agency, and he receives a most curious request—to attend the service in the guise of his client.

Tension hangs between the mourners, and it turns out that none of them have so much as seen the event's host. But things only go from bad to worse when the ferry set to return them to the mainland never shows up... and the guests discover the servant who had been attending them murdered.

(Source: MangaGamer)