User blog comment:B214/Question & Answers 5/@comment-207.96.205.2-20160517060930/@comment-27876048-20160519001513

Maybe this will put this in context:

For Aristotle (384–322 BC) mind is a faculty of the soul. Regarding the soul, he said: It is not necessary to ask whether soul and body are one, just as it is not necessary to ask whether the wax and its shape are one, nor generally whether the matter of each thing and that of which it is the matter are one. For even if one and being are spoken of in several ways, what is properly so spoken of is the actuality. — De Anima ii 1, 412b6–9In the end, Aristotle saw the relation between soul and body as uncomplicated, in the same way that it is uncomplicated that a cubical shape is a property of a toy building block. The soul is a property exhibited by the body, one among many. Moreover, Aristotle proposed that when the body perishes, so does the soul, just as the shape of a building block disappears with destruction of the block.

In summary Aristotle believes that the mind and the soul are connected. This whole soul situation opperates (in my opinion) under the same principle. Because Issei has the mind of a human then his soul is also that of a human.