Protalizabetta is a young girl who has just escaped from her wedding. She has always wanted to see the world and meet the love of her life, and now that she is free of obligations, she decides to fulfill her dreams, but there is just one problem: a demon crosses her path with the intention of devouring her heart. Prota, determined to avoid this, proposes an unusual pact to the devil: if she helps her kiss 100 monster girls in a year, she will let her eat her heart.