The 57th spirit of the Goetia and a great President of Hell. He first appears as a leopard, but after some time will take the form of a man. He gives skill in all liberal sciences and true answers concerning divine and secret things. He can change any men into any shape the exorcist may desire, and the one that is changed will not know it.
He can also put them in a state of insanity on which the victim will believe that their identity has changed. The delusion, however will only last for an hour. Ose governs over 30 legions of spirits.
"Origin: Israel. One of the 72 demons of the Goetia. He is a President of Hell. He has a giant panther head and can change a person's appearance without them noticing. He can also inflict various delusions and fantasies upon people. In addition, he can make his summoner into an outstanding scholar."
Ose appears after the summoning ritual involving Saki is completed, his body towers over many buildings and he does not speak. He proceeds to fight Masakado and Cerberus, but is being easily beaten by them. In order to counter this Gagyson offers his life to his master, which gives Ose wings, tusks and birdlike feet. Despite this, he was still losing until Masakado let his guard down, after catching Masakado in his hand Ose's lost arm regenerates thanks to his unlimited supply of magnetite coming from Saki. Once he loses his unlimited supply of magnetite Masakados finishes him off in one blow.
Ose can only be acquired through fusion and appears as a boss in one of the final acts and as support for many of the bosses following his act-- in particular he appears alongside Flauros in the Distortion boss room. In Act 18 he faces off against Andras, Azura, and the player character, summoning Berith and Orobas to aid him. After losing he is disappearing as his two allies have already vanished. He uses the last bit of his strength to strike down Andras, only for Azura to take the blow meant for him, vanishing afterwards.
During the Basilica activation quest, the player encounters Ose Hallel when it kills a Demon Buster in front of them, scoffing that humans are weak no matter which world they belong to. After the fight, he leaves, but reappears to confront the player and Azura in Nakano, where he is fought off by DB Kuroe. He appears alongside Flauros Hallel as the third boss fight in End of Days Ichigaya. After obtaining his plug-in, players are able to fuse this variant in a special double-fusion of Ose and Throne.
Ose is summoned by the Terminal Guardian at the third terminal to defeat the prentice Samurai. His defeat leads the terminal to return to normal. He will also be summoned by G.H. Hills in the final round of the "Hunter Tournament Finals" Challenge Quest.
Ose initially appears in Kanda-no-yashiro, guarding a crest which unlocks the seal which holds Krishna prisoner. Nanashi must defeat him in order to obtain the crest needed to proceed further into Kanda-no-yashiro's depths.
Ose will later appear as a regular enemy in Shibuya. He can teach the Blight, Critical Wave and Javelin Rain skills through his Demon Whisper. Ose benefits from learning Physical attack skills.
The Shadow of Yoshikuni Nejima takes the form of Ose when the party encounters him in Mementos. Due to his cheating in the real-world games making him impossible to hit, the Phantom Thieves will likewise be unable to strike him during the battle. After a few turns, the initial battle ends with the party retreating. In order to deal with Shadow Nejima, the protagonist must seek out information on a skilled game player, Shinya Oda. After learning some tips from Shinya, the protagonist will be able to land a hit with his gun the next time Shadow Nejima is encountered through the use of a special shot. The battle then ends with an all-out attack from the Phantom Thieves.
Known as Ozemos, he appears as a boss guarding one of the doors in the final dungeon, Dark Castle Tyrnanog. Stating that Jin's quest to defeat the Imperium will end here. After his defeat he is impressed by Jin and states that Imperius waits ahead.
Ose is one of the three commanding officers of Remiel. After fellow officer Crocell is defeated, he takes action in going against the Devil Children, sending Raphael to act as a spy while sending other servants like Poseidon and Ameretat to take them down. He later invites the group into his castle by letting them believe he is giving them the tool they need to defeat his master, only to challenge Jin and Akira to battle. Once Jin proves he has what it takes to defeat Remiel, he gives him the item. The last officer Gemori appears before them and tries to kill both him and Jin, with Ose protecting Jin and dying in the process.
Ose in Tokyo Revelation is called Satan in the English dub, but is called President in the original Japanese version.
Prior to the PlayStation 2 era, Ose's sprite was a palette swap of Flauros's; the artwork was even dedicated to the latter. In Shin Megami Tensei III: Nocturne, even though both Fallen demons received updated designs, Ose's 3D model was based on Flauros's outdated design with his original skin palette, while Flauros's model is based on the updated design. This continued in all subsequent games which use 3D demon/Persona models until Persona 5 in which Ose's 3D model was based on the revised artwork.