1. A blood vessel analysis apparatus comprising: a storage configured to store data of a time-series medical image of a blood vessel of a subject; and processing circuitry configured to temporarily structure a dynamical model of analysis processing based on the time-series medical image, identify a latent variable of the dynamical model so that at least one of a prediction value of a blood vessel morphology and a prediction value of a bloodstream based on the temporarily structured dynamical model is in conformity with at least one of an observation value of the blood vessel morphology and an observation value of the bloodstream measured in advance, analyze the dynamical model to which the identified latent variable is allocated, and temporarily structure a dynamical model of analysis processing of an analysis target region, based on a time-series morphology index, a time-series shape deformation index, and the time-series medical image.