The New School Term Has Started

is episode 25 of the Beelzebub anime.

Summary
The students of Ishiyama High School settle in at Saint Ishiyama Academy, with all the significant characters being placed in the same classroom. Their new homeroom teacher, Sadohara, challenges Tojo to an arm wrestle to try to establish some authority over the class, failing miserably when Tojo accidentally slams him upside-down against the wall. He then picks a second target, Oga, who was sleeping in his seat, and wakes Oga in order to challenge him. Baby Beel is angry to have been woken and subsequently tantrums, shocking Oga and Sudohara. An aspiring delinquent from St. Ishiyama, Kazuya, goes searching for Oga after hearing rumors of his strength, bringing his childhood friend Azusa with him. A gang pick a fight with Oga and Furuichi in an alleyway, and upon fighting back, a gang member grabs Kazuya and Azusa, who were watching from the entrance of the alleyway, and threatens to hurt them if Oga does not submit. Aoi shows up and frees them, allowing Oga to now beat the gang senseless. As he's beating them, Baby Beel has a tantrum, electrocuting all of the gang members and Oga. Kazuya confuses this for Oga's attack. After leaving the alleyway, Kazuya begs Oga to take him under his wing.