- "Sector Delphinus looks like an open-area filled entirely with waste. Huge structures made of waste line the sector. It's like a city of the dead, where all life has ended..."
- —Black box data, Shin Megami Tensei: Strange Journey 
Sector Delphinus is an area in which the landscape consists of piles of waste and refuse. Skeletons of dead creatures can be seen by the walls of garbage and even inside them. Puddles of oily muck and drums marked for radioactive hazardous material can also be found scattered throughout the sector. The first mission through Delphinus is to find the Rossetta most likely in possession of a demon in the sector, however soon after arriving an additional task arose: to find Commander Gore's body, which is discovered to be missing by the sickbay crew shotly after arriving in the sector.
This sector features conveyors covered in muck that will move the Protagonist as soon as he steps on them, leaving him powerless to resist their movement.
Upon reaching Delphinus' 4F, the Protagonist is confronted by a revived Gore, who demands to know the Protagonist's intentions and demands he submit to the will of the Schwarzwelt. However, before they come to blows, he is summoned away. Soon after this, crew members are infected with an unknown disease that heightens aggression and madness. The Protagonist and Zelenin realize it is similar to the symptoms Crewman Norris presented while being experimented upon in Sector Bootes; Jimenez is one of those afflicted.
Studying the few captured crewmen, Arthur rapidly dictaminates the cause of the plague is a mental parasite, an energy source that nestles within the crewmen and causes the mindwarp. Establishing the connection between Bootes and Delphinus, he has a mission posted to raid Mitra's labs for information.
With the new unlocking programs created with Delphinus' rare forma, Zelenin and the Protagonist unlock Mitra's private laboratories in Bootes and find Mastema, who translates several plaques for them, one of the room's relics being the Madman's Stone, a crystal created to induce violent insanity upon humans by a joint effort between Mitra and Asura, Delphinus' apparent ruler. With the information gleaned from the Stone, Arthur has several MK Guns, devices designed to induce altered states of consciousness, modified to create energy waves capable of dispelling the Delphinus Parasite, though heavy objections are raised when the crewmen learn the ship carried what essentially was tantamount to brainwashing equipment.
Upon using the device with the infected crewmen, several glowing orbs are expelled from their bodies. As the Protagonist and Zelenin reach the higher levels of Delphinus, they find huge hives where the released orbs are amassing; they find no definite trace of Asura, but rather a scattered road of energy that leads to the hives.
In one of the hives, the gathered energy speaks to Zelenin, accusing her of being unable to trust anyone and mocking her; her Power is unable to fully protect her. Upon the destruction of several of the hives, all of the orbs leave the hives and race for a statue in one of Delphinus' higher levels; combining together, they form Asura, Delphinus' demon ruler. Asura states he intends to "polish" human spirit by removing everything but raw aggression and rage; the Protagonist will confront and destroy Asura after an alignment-affecting choice and reclaim his Rosetta to reach Sector Eridanus.
Later in the game the Red Sprite crew return to Delphinus to retrieve the Cosmic Egg. The Egg is hidden on the highest floor and is protected by Law demons. When the Protagonist finds the Area with the Egg itself he meets a Cherub, which will fight him on the Chaos and Neutral Paths. On the Law path he gives the egg to the Protagonist.
Demons appearing in Sector Antlia include:
- Ame no Uzume
- Yuki Jyorou
- Asura (Sector Boss)
- Futotama (Enemy Search)
- Kurama Tengu (Enemy Search)
- Hare of Inaba (Enemy Search)
- White Rider (Enemy Search)
|Characters||Protagonist - Gore - Jimenez - Zelenin - Arthur - Bugaboo - Captain Jack (& Jack's Squad) - Ryan - Mastema - Louisa Ferre - The Three Wise Men - Mem Aleph - Kato - Williams - Muccino - Irving - Chen - Terry - MacCleary - Dent - Mia - Gekko - Anthony - Blair - Zoe - Maebe - Wolf - Tyler - Mackie - Mike - Dawson - Keema - Norris - McClane|
|Locations||Red Sprite - Sector Antlia - Sector Bootes - Sector Carina - Sector Delphinus - Sector Eridanus - Sector Fornax - Jack's Squad HQ - Sector Grus - Sector Horologium|
|Terminology||Schwarzwelt - Demonica - Demon Summoning Program - Delphinus Parasite - Magnetite - Macca - Moon Phase System - Cosmic Egg|
|Lists||Demons - Bosses - Skills - Forma - Equipment - Items - Apps - Extra Missions|
|Music||Shin Megami Tensei: Strange Journey Original Soundtrack|