The body is a "vessel"

The contents match the (heart) container. It changes shape to match.

I was remodeled by the Demon King army and have become a woman.

The psychological effects are inevitable.

...But I will definitely return Master to his original body!

Hehe.. how reliable but there are things that I've come to realize now that I'm in this position.

Even though you are my student. You've grown up to be a fine man.

Eh? What.... hello?