Kazbiel (also known as "Kazbeel" and "Kazbel") is a fallen angel in Jewish mythology, known as the "angel of the oath". His name means "he who lies to God". His original name was Biqa, meaning "good person". Kazbiel attempted to coerce Michael to tell him the hidden sacred name of God, but he was denied.
In the Megami Tensei series, he is instead referred to by the different pre-fall name of "Kazfiel", which appears to be derived from Kafziel.
"The sinful 'angel of the oath'. His original name was Biqa, meaning 'good person'. He attempted to coerce Michael to tell him the sacred name of God, but was denied. After the Fall, he was given the name Kazbiel, 'he who lies to God'."
—Shin Megami Tensei: Strange Journey Compendium
Kazfiel appears as a summonable demon and an optional sub-boss in Sector Eridanus 3F. Once he has been defeated, both alone and fighting in tandem with Aniel, they will scan the Protagonist's soul. If they find it to their liking (Law Path) they will unlock the door sealing Mother Harlot, the most powerful of the Fiends, and beg the Protagonist to slay her and her dragons. While depending on the Protagonist's choices she can even flee the battlefield after her defeat or be devoured by her beasts, Aniel and Kazfiel will both praise the Protagonist and reward him with the most powerful Law-aligned sword in the game.
Kazfiel appears in the Challenge Quest, Escorting Your Comrade . He appears in Naraku before Flynn can reach the Sky Terminal with Navarre, stating that it is the Lord's will that he be slain as he is unworthy, only to die in combat. He is later on the Chaos and Neutral routes in Purgatorium - 1st Crown, where he and the Deadly Divines have set up a barrier that blocks the way further in.
"The sinful "angel of the oath". His original name was Biqa meaning "good person". He attempted to coerce Michael into telling him the sacred name of God, but was denied. After the Fall, he was given the name Kazbiel, "he who lies to God"."