Due to the after effects of Super Milk Time, Baby Beel and Oga have swapped bodies. In order to return things back to normal, they try to look for Saotome-Sensei to see if he knows how to, however they are continuously disrupted by everyone else from the academy trying to start a fight with Oga (who is currently Baby Beel). Eventually, Baby Beel runs away after being drawn to a smell, and Hilda, Furuichi and Oga try to catch him, where they find him attached to Aoi. After hugging Aoi, BabyBeel runs off once again and so Hilda and Aoi have a match to see who can catch Baby Beel. Although at the end BabyBeel chooses Aoi over Hilda after she shows some of her new demon magic from training. Not long after, Aoi and Hilda attack Oga(Baby Beel) when fighting over him, and just before they hit him Oga and BabyBeel return to normal, leaving Oga being severely hurt by the two and BabyBeel perfectly fine. Saotome-sensei then comes to school the day after.
La guerre se prépare entre les camps d'Ishiyama et d'En'ô. Si Oga est parvenu à repousser ces derniers en se synchronisant au maximum avec Beelzebub, il a oublié que cela avait des effets secondaires. Lorsqu'il se réveille enfin, il constate que son corps et celui de Beelzebub ont été intervertis. Lui et Hilda vont devoir trouver Saotome afin de ramener la situation à la normale...
Después del enfrentamiento contra los Pilares de Behemont, la fusión entre bebé Beel y Oga sufrió un pequeño efecto secundario, se intercambiaron sus cuerpos. Ahora, con bebé Beel en el cuerpo de Oga, deberán intentar que no se escape y llamar la atención lo menos posible. Oga busca a Saotome para que le ayude a recuperar su cuerpo pero cuando intenta buscarlo en el colegio, éste no está presente.
Si inizia con gli esercizi "Pudding-Pudding" e poi a scuola con i corpi scambiati. Chi sceglierà Baby Beel? Kunieda o Hilda? DOSKOI!!!
