The Detective Is Already Dead, Vol. 1 (manga)

The only survivor, me, and the detective's dying wish: their unfinished story. I, an ordinary high school student, Kimihiko Kimizuka, I was embroiled completely flawlessly into a plane hijacking, Where I became the assistant to the angelically beautiful detective girl I met. In three years, the great detective and her assistant unfolded a dazzling adventure dram-- Before long, we were separated by death. This takes place a year after that. The only survivor, me, and the detective's dying wish--