Before the events of the game, Belphegor arrived in Arbor, but he was eventually sealed in the roots of the tree, along with the Lux spell. Years later Torte came to Arbor searching for Lux and opened the chest holding it, in the process, Torte broke the seal that trapped Belphegor and set him free. Belphegor traveled to Mount Gulg and planned to set off the volcano. On the mountain he encountered Arbaroc, the guardian of Arbor, Belphegor then planned to use Arbaroc's body as his own. Torte tried to prevent this, but he was knocked out by Belphegor and thus unable to stop the demon from possessing the guardian beast.
Fifteen years later, Brandt and the others travel to the Great Tree and encounter Belphegor, in Arbaroc's body, at the top. The party is forced to fight him and they manage to defeat him. The death of the possessed Arbaroc, apparently along with Belphegor himself, ultimately leaves Arbor without its guardian.
After the party is sent back in time, they meet up with Torte the moment he released Belphegor. After Belphegor is released, the party travels to Mount Gulg in order to stop him from setting off the volcano. At the top of the mountain, the party witnesses Belphegor attempting to possess Arbaroc's body and intervene only after Torte is knocked out.
With Belphegor destroyed, his possession of Arbaroc never occurred and Arbor is at finally at peace. Later, Belphegor is revived within the Star Chamber, but he is defeated once more.
Belphegor is fought twice in the game, once at Mount Gulg and another time in the Star Chamber. Belphegor and the cubes mainly uses fire-elemental attacks.
Belphegor once again appears as a boss. He can be encountered once the player examines the monument on the peninsula east of Caldisla. In addition, Belphegor makes a cameo appearance when using the Sloth and Firaja abilities.
Like the other major demons in the game, Belphegor references one of the seven princes of Hell in demonology, each one representing one of the seven deadly sins. Belphegor is a demon and one of the seven princes of Hell who suggests ingenious inventions that will make people rich, although Bishop and witch-hunter Peter Binsfeld believed Belphegor to tempt by means of laziness. According to Peter Binsfeld's Binsfeld's Classification of Demons, Belphegor is the chief demon of the deadly sin Sloth.In demonology,
Belphegor originated as the Assyrian Baal-Peor, the Moabitish god to whom the Israelites became attached in Shittim (Numbers 25:3), which was associated with licentiousness and orgies. As a demon, he is described in Kabbalistic writings as the "disputer," an enemy of the sixth Sephiroth "beauty." When summoned, he can grant riches, the power of discovery and ingenious invention. His role as a demon was to sow discord among men and seduce them to evil through the apportionment of wealth.