This is referred to as gokuraku ojo (peaceful death). whereby 'o' means to go to the Pure Land (of Amida Buddha), 'jo' means to kesho (be reborn) in that land and to be reincarnated in the Pure Land is referred to as Renge kesho.
これは極楽往生（ごくらくおうじょう）といわれ、往とは極楽浄土にゆく事、生とは、そこに化生(けしょう)する事で、浄土への化生は蓮華化生という。