Issei-chan & the Demon King (Queen) of Sixth Heaven

Falling into a magic circle is one thing. Meeting a scary gun lady inside of it? That was scary. But turning into her, succeeding her, and inheriting her legend? Yeah, that was the icing on the cake. Issei was perfectly fine with that, though, and if anything, the gender change was secondary. (Or so she learned.) Girl!Issei. Yes!