This is definitely one of those isekai where I have to not think too hard about the moral and existential implications of the ambiguity of whether the protagonist is, or is not, truly the character whose body they now inhabit.
(If not, the implications are horrendous. Well, that said, suspension of disbelief is often important to enjoyment of a good work of fiction—it's just interesting the extent to which it's convention for this genre to whistle it's way past such problems.)