The font design process differs depending on the designer. However, there are many cases in which the italic design begins after the regular design is fixed to some extent in the case of a font family containing regular and italic. The reason is that it is easier to compare the difference between the two after the outline of one design is decided rather than composing two styles simultaneously.
Focusing on several points regarding part shape, etc., including inclination angle, character width, character shape, beginning of the pen stroke, and ending of the pen stroke, the difference with regular can be compared.
In Hama Mincho Italic, the italic design is composed based on the already released Hama Mincho Regular.