"You can't just manipulate people to do whatever the hell you want!"
—Heat O'Brien, Digital Devil Saga: Avatar Tuner 2

Heat O'Brien is the human upon which the AI Heat was based on.

Appearances Edit

Design Edit

O'Brien looks visually identical to the AI bearing his name, except for his wardrobe, eyes, and hair. Also, the human Heat was somewhat blond, while the AI had bright red hair.

In Quantum Devil Saga book 3, he has red hair unlike his in-game counterpart. 

Personality Edit

As hot-headed as his AI counterpart, he would often make angry outbursts at how Sera was being treated, and openly expressed his disgust of the manipulative behavior of his coworker Serph Sheffield. This caused Sera to regard him as a scary big brother, as she never saw the side of him that cared for her.

The AI Heat is based upon the hotheaded, angry side of Heat O'Brien that Sera regarded with fear. Like Heat O'Brien, the AI Heat comes to care for Sera deeply, though he is unsure exactly how he feels about her, reflecting Sera's own confusion of their relationship, and can only express himself with anger and force.

Profile Edit

Digital Devil Saga: Avatar Tuner 2 Edit

Heat O'Brien is a graduate of Berkeley College as a gene therapy doctor, who joined the Karma Society's God Project and was placed in charge of Sera's physical condition. His little sister died of the Cuvier Syndrome, and he came to care for Sera as a replacement sister, giving her a black cat named Schröedinger as a present.

While Sera was being put through a painful and particularly damaging experiment which he believed she had little chance of surviving, Heat finally snapped and pulled a gun on Serph, ordering him to stop the experiment for Sera's well-being. However, he was shot in the back by Argilla's human counterpart and died. One of the scientists accidentally engaged a live feed of the control chamber into the test chamber where Sera performed, allowing her to watch as Heat died.

As a result of the horrific revelation, Sera inadvertently poured enormous amounts of corrupt data into her communication with God, maddening the entity with pain, causing the Black Sun incident.

His Solar Data was preserved, and collaborated with his spiritual successor, the AI bearing his name, and Serph, the AI version of the maniacal Sheffield, to destroy the remnants of the Solar Data of the lunatic and of a fake version of the AI originally used in the Junkyard. Following this, he finally died for good.

Quantum Devil Saga: Avatar TunerEdit

Unlike Shin Minase, who is still alive, he has the role of a posthumous character. Instead of being American-Irish like in the game, he's German and his name is Kazuki Homura. 

His name is first mentioned in a scene that never happens in the game, when Serph and Heat face Varin Omega in the Junkyard: Varin, having met Shin Minase before, knows the truth about the Junkyard AIs and calls Serph and Heat by the names "Shin" and "Kaz".

He's the protagonist in book 3, which is a prologue for the entire story revolving around him and the circumstances of his death. He's an Empath and is in a relationship with Shin's sister Kei, and unlike the game, has dark-red hair which is a sign of his supernatural nature. He's been tasked to work with Sera and, after seeing her acting cruel and not caring for the deaths of many people, attempted to break her mind, forcing her to feel all the rage and sorrows he had felt. It's because of that operation that Sera contacted God and turned the sun black. 

He gets killed by a man named Henry Marcus who transforms into Michael. 


True Heat as Agni acts as the temporary party member alongside Serph against Real Varna and Fake Varna. Because the enemies are pathetically weak and True Heat's skill repertoire is well geared, players can simply pass Serph's turn for True Heat and let him handle the rest. He can neither participate in or initiate any combo skills nor revert to human form from Agni.

Level Race HP MP Drops
 ? n/a ~330 ~280 n/a
Resists Void Absorbs Reflects Weak
List of Skills
Skill Effect
Agidyne Heavy Fire damage on 1 enemy.
Skull Cleave Heavy Physical damage on 1 enemy.
Chi Blast Moderate Physical damage on all enemies.
Mediarama Recovers HP moderately to party.
Diarama Recovers HP moderately to 1 party member.
Tarukaja Increases Physical power by 1 level to party. Can stack up to 3 times.
Power Charge Boosts user's next Physical attack damage by 150%.
Samarecarm Revives 1 party member with all HP recovered.

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