The last chapter in the four-volume Phase D sci-fi visual novel series. There are four phases of human existence. From conception to birth is called Phase A. From birth to death is called Phase B. From death to disappearance of the corpse is Phase C. And last, remnant after the death, separate from the corpse, is referred to as Phase D. (from https://www.mobygames.com/game/psp/phase-d-akehime-no-sh )