Onna Yuusha ni Tensei shitara Mazoku no Tsuma ga 5-nin mo Iru Rashii

Unlucky-in-life Reiko goes to bed one night dreaming about what it would be like to be a different person... and then she wakes up in the body of Laina, the hero of (insert isekai realm here)! But all is not well in paradise, and the future of the world may hinge on Reiko satisfying all five of Laina's demonic wives, including the beast champion Gagaka! Can Reiko protect her virtue, or will wifey number one make her howl!?

(Source: Irodori Comics)