Nanananoka (the 49th day from the date of one's death) (Shijukunichi, Man chuin, Jinshichinichi)---'Dairenki (the 49th day from the date of one's death)' is thought to be the most important memorial service.
七七日（なななのか）（四十九日、満中陰、尽七日）…「大練忌（だいれんき）」、もっとも重要な法要とされる。