[SPOILER ALERT! PLEASE READ VOL 3 ONWARDS OF THE LIGHT NOVEL BEFORE CONTINUING. OR READ AT YOUR OWN RISK!] [EDITED SUMMARY] Alas=Ramus came to Earth and appointed The Hero and The Demon Lord to be her parents. Of course, that's completely impossible since they're enemies. But how can they abandon such a cute baby? After some incidents that happened that involves the baby, The Hero is now fused with her! She doesn't have any other choice but to take care of the baby. But what about the Demon Lord? Alas=Ramus was actually the plant that The Demon Lord took care of for so many years. So technically, he really is the father of Alas=Ramus. I, The Hero Emilia, now goes by the name of Emi Yusa, was forced to ask The Demon Lord, my enemy but the father of my daughter to go shopping with me. That's just easy and simple, right? Well, not for the Hero and the Devil. A lot of complicated things happened in just one day. Why? Read and find out. This is the story of "My Day with The Devil".

if you haven't seen the anime or read the manga you might not understand

As our usual team, the Spartoi gang, catches a certain… Kishin(?), they find their worlds colliding with great danger… What would happen if their worlds collide, because of a man's own work ? Was it fated to happen ? If it is, why ? "Failing would mean death—both of us and the human race." What are THEY gonna do when all hell breaks lose ? "Are you all ready to face this ?"