This book describes a novel method for mortality modeling applying the shifting feature of the mortality curve. In Japan, the increase and pace of the extension in life expectancy have been quite remarkable. Therefore, existing mortality models often cannot capture the peculiarities of Japanese mortality, nor can the Lee–Carter model, which is now regarded internationally as a standard model. One of the important concepts to model recent Japanese mortality is a shifting feature. In this book, the linear difference model, which has many advantages for modeling and analyzing Japanese mortality, is introduced. The book shows applications of the model to mortality projection with a tangent vector field approach and decomposition of the change of modal age at death. The models introduced here are useful tools for modeling mortality with strong shifting features, as in Japan.