Prior to the events of the game, Beelzebub arrived in Urbeth, the City of Faith, and caused a terrible plague throughout the area. Beelzebub and his minions disguised themselves as merchants selling Hi-Elixirs to cure the disease; however, the prices were expensive, causing many people in the city to die for lack of money. Beelzebub then called the high ranking elders of the city to the Tower of the Sky, where he convinced them that money was the most important thing, and caused them to lose their faith. The city became the City of Merchants after these events.
After the party is sent back in time, they arrive in Urbeth during the time of Beelzebub's plague. The party discovers Thauzand's daughter is infected with the plague and they are sent to buy a Hi-Elixir from Beelzebub, who is disguised as a merchant. When they arrive at the fiend's shop, he naturally charges a heavy price for the Hi-Elixir. The party learns that the Hi-Elixir can be found in the Hunting Caves and travel to the lowest level of the dungeon.
There, they are attacked by one of Beelzebub's minions, who is defeated. The party goes to the Tower to the Sky just as Beelzebub attempts to corrupt the elders, where they stop him and reveal his true form. The party battles and defeats Beelzebub, restoring the city to its original form. Later, Beelzebub is revived within the Star Chamber, but he is defeated once more.
Beelzebub is fought twice in the game, once at the Tower to the Sky and another time in the Star Chamber.
Beelzebub is stated to have been once a king of men who became worshiped as deity until he is demonized into a Sin Beast by the Crystal Orthodoxists. Beelzebub was keep at bay by Yōko until she is defeated by Yew Geneolgia's group, who attempt to keep it from going on amok upon emerging from the monument east of Al-Khampis. Users of the Yōkai asterisk can summon Beelzebub to use his Gluttony and Acid Breath abilities.
Beelzebub means "Lord of the Flies" in Hebrew and is a name often associated with the devil. It appears in the book by William Golding of the same name (Lord Of the Flies) as the head of a slaughtered pig on a stake. Beelzebub is also one of the Seven Princes of Hell, associated with the deadly sin of Gluttony.
Like the other major demons in the game, Beelzebub refers to one of the seven princes of Hell in demonology, each one representing one of the seven deadly sins.