Behemoth

is the leader of the powerful army that works directly under the Demon Lord and Lord En. He has been mentioned several times, but finally did his first appearance after the Oga/Beel Body Switch incident, looking for Oga in the Saint Ishiyama building.

Appearance
He has the appearance of a simple old man, though this could be only a disguise, as his powers were clearly threatening

Personality
Being introduced in his old man form he is shown to be calm to the point of not reacting to four opponents attacking him only to transfer to right in front of Oga to issue a war declaration. He claims that his reason for stepping down as general is due to old age.

Even though his son was removed from the Pilar Division due to his temper, Behemoth still reinstates him as the general because he wishes to see his son succeed him.

Plot
He easily defeated Hiromichi Gō and Ichirō Shinjō and then proceed to search for Oga. He was later ambushed by Ittōsai Kunieda, Genma Isurugi and Zenjūrō Saotome, though he didn't fight them back, saying that he only came to greet his new neighbors. He then revealed to have build the Akumano Academy in the grounds that used to be Ishiyama High.

Despite his earlier claims, once he met Oga face to face, he declared war on him and his group, but denied that he was the general of the army. He then introduces Jabberwock, who suddenly appears next to them, as the acting general. As his son summons Sodom he jumps on the dragon as well and discuss Oga's skills with his son. When Oga appears on Sodom he stands back and allows Jabberwock to fight him alone.

He later appears in his office at the Akumano Academy revealing to Hilda that she was captured because En wanted a new Wet-Nurse.

Fighting Style
Although he hasn't been seen fighting, it can be noted that he is exceptionally strong, seeing as he was the leader of Behemoth's 34 Pillar Division. Plus, he was able to beat beat both Hiromichi Gō and Ichirō Shinjō.

Ryuhey Tamura said, in the next chapter, Behemoth Would Fighting with Oga. Behemoth is Stronger then aoi grandfather