1. A method for acquiring hair characteristic data, comprising: acquiring a cross-sectional image of a human hair, in which a plurality of types of fibrous tissues constituting cortex cells present in the human hair are visualized in such a manner as to be distinguishable from each other; acquiring, from the cross-sectional image, numerical information indicating a distribution state of the visualized plurality of types of fibrous tissues, the numerical information including a distance between a centroid of a distribution of a first intermediate filament tissue in the cross-sectional image and a centroid of a distribution of a second intermediate filament tissue in the cross-sectional image; acquiring calibration data indicating a relationship between the numerical information and a hair characteristic using human hair samples as reference hairs; and evaluating a hair characteristic of the human hair on the basis of the numerical information of the human hair and the calibration data indicating the relationship between the numerical information and the hair characteristic using the human hair samples as the reference hairs.