A while after, Oga discovered a symbol on the back of his right hand. Hilda explains that it is the fly king seal more commonly known as the zebub spell, the family crest of the royal family. The appearance of the seal means that he has officially made a contract with beel. She also explains that the more evil he is, the more complex the design of the seal will become. Oga attempts to prevent the seal from growing by preventing himself to get into fights, but eventually has to give up. This is due to Himekawa, the second of the Touhoushinki, capturing Hilda and Furuichi, so he infiltrated Himekawa's base and defeated him by using the zebub blast for the first time. The consequences of using it caused the crest to stretch across his arm, Hilda commented after looking at the crest that the amount of energy used that time would have driven a normal person mad.
|Beelzebub (べるぜバブ, Beruzebabu)|
Aoi, who was apparently away from school during the first two events, returned to school to defeat Oga, as she failed to find his name last time, to prevent him front causing any more trouble within the school. But on encounter, she realized that she had already met Oga, but not vice versa. After he dodged her attacks twice, he notices beel's interest in Aoi and so says"Please become this kid's mother"that causes another misunderstanding, when it was actually a request for her to replace him as a parent. The fight is postponed, and Hilda soon arrives to give beel's milk. The MK5, which returns later in the manga, make their debut in the story only to be defeated in a five panel pattern to be used again later in the story. After the fight beel senses something which turns out to be the last of the Toushinki, Toujou. Oga, however, did not notice.
Aoi sees Oga and Hilda's fight with MK5, and believes in the rumours that they are husband and wife. She is challenged by Hilda to a fight so she can test her ability, the fight ends quickly with Hilda deciding that Aoi wasn't on the same level as Oga. At the same time Oga was confronted by Chiaki and Nene. Two female students told Aoi that Oga had injured the two of them, which later turns out to be MK5.
Aoi fights Oga to avenge her two classmates, while Oga was assuming that she wanted to accept the role of becoming beel's parent. Nene, at the same time, woke up in the infirmary and goes to warn Aoi of MK5's trap, which turns out to be schemed by Miwa. MK5, however, prevents anyone from interupting Aoi and Oga's fight. Nene was about to get shot, but Natsume appeared and fought with MK5 to allow Nene to tell Aoi. She was unfortunately too late, as Aoi had already seemed to defeated Oga and was just in time for Miwa and Ikari to take over.
Oga suddenly gets back up and defeats Ikari and Miwa easily. It is then shown that Furuichi and Hilda have been watching the whole time. Oga, Furuichi, Hilda and baby Beel went to the beach in search for Toujou to hand baby Beel over to him, not knowing as this was a plot set by Kanzaki and Himekawa for both Toujou and Oga to crush each other. Aoi went to the beach as well to warn Oga about Toujou's strength. Oga and the gang had troubles searching for Toujou and were set in a wild goose chase. Oga decided to write a letter of challenge to Toujou and have Aoi pass it to him. Aoi attempted to tear it but one of Toujou's henchmen found it. They were supposed to meet between the two rocks at 5 pm. Oga was confronted by the MK5 once again but Oga quickly defeated them and arrived late. Toujou left after crushing several motorcycle gangs which inspired Oga to find Toujou .
|Tatsumi Oga with demon|