The Weight of the Fists (拳の重さ , Kobushi no omosa) is chapter 196 of the Beelzebub manga.
Summary[]
After a startling punch to the face, Nasu lies on the ground wondering why he is the one looking up at his opponent, who proceeds to tell Nasu that he will educate him on who is really oblivious in their situation. This aggravates Nasu who then rises up on his feet. He declares his current thoughts on the fight and the apparent strengths of their Demons. Nasu moreover asks what the "Father Switch" is before resuming his battle with Oga.
Nasu conjures several Emblems that he subsequently uses to boost his speed. He attempts to punch Oga though his fist is blocked; afterwards, he receives a series of hard blows from Oga, who explains with each attack on how unfit Nasu is to even touch Baby Beel. Having received another beating, Nasu wonders again why it is all happening to him, especially by someone unable to properly use Spells. He tries to reason with the circumstances.
On the top of a rooftop nearby, a young individual, who has apparently been watching the fight from afar, notes how Nasu is apparently reaching his limit. He communicates with an unknown third-party via cell phone, telling the latter to channel his power into Nasu, as payback after the delinquent was previously "loaned" a Demon.
Nasu suddenly begins to feel an overwhelming sensation flow throughout his body; realizing the perpetrator, he curses the latter. Soon after, several identical clone-like figures of Nasu appear throughout the room, which he explains is due to one of his Demon's abilities. He briefly explains about them before declaring that Oga cannot stand a chance against him. However, Oga suddenly starts drinking from a metallic container, and upon finishing, tells Nasu to come at him; this provokes the "Beast" into attacking Oga along with his clone-like figures. Oga then activates Super Milk Time, plus the "Father Switch", after consuming his 600cc. Now merged with Baby Beel, he violently punches Nasu and his clone-like figures into the ceiling above, effectively burying all of them in a straightforward formation.
This unexpected attack astonishes everyone else present during the battle. Oga, on the other hand, says to himself how he won't lose to someone that shirks his responsibilities.