Crown Prince Cecil has wed Bertia, the self-proclaimed villainess. The two are now enjoying their happily-ever-after in what can only be described as the ultimate devoted love journey. However, their peaceful days are fleeting when Bertia's friend, Lysonna, reaches out with a special request-she wants Bertia to help plan her wedding. Still glowing from her own grand ceremony, Bertia eagerly travels to the Kingdom of Umyuve to reunite with Lysonna. Still, something feels a bit... off.

To her surprise, Bertia realizes that Lysonna is actually a character from the very novel she read in her past life-and worse, Lysonna was the villainess, notorious for tormenting her younger stepbrother and his fiancée out of jealousy. Determined to protect everyone's happy ending, Bertia, once a top-tier villainess, makes a bold declaration: "I'll step in as your stand-in villainess!"

And so, the curtain rises on Bertia's new role as the world's first Proxy Villainess!