Voiced by: Issei Miyazaki / Yuri Lowenthal

Sol's student and the illegitimate son of Ky Kiske and The Maiden of the Grove, a Gear woman who was recently confirmed to be Dizzy. He travels with Sol due to his Gear nature, which makes him an easy outcast. Sol is more of a father figure to him than anyone else, even his biological father, Ky. Sin deeply resents and hates his father for not being there for him after he was crowned King of Illyria. Ky gave him very little, if any, attention, making their relationship very distant. All of the attention was given to him by his mother. Because of his very fast growth rate, he was placed in Sol's care for the discovery of his existence will endanger his life.

Since he was raised under Sol (and no thanks to his surprisingly young age), Sin is very hotheaded and charges into things without a second thought. This trait ends up getting him kidnapped and brainwashed by Valentine to serve her. The brainwashing fuels his desire to surpass his master, and increases his rage towards Ky. He is eventually beaten out of his condition by Sol, and continues to fight Valentine's Justice form. When Valentine attempts to self-destruct the gate to the Backyard, Sin is forced outside the gate by Sol. After the End, it's shown that he's now trying to mend the broken relationship with his father while awaiting for the recovery of his mother, deciding to take it slowly and continue to train under Sol.

Voiced by: Toru Furusawa / Dave Wittenberg

A jovial fox spirit created in the Backyard. He lives in (and was previously exiled to) a pocket dimension of the Backyard called the "Yomotsu Hirasaka" or Underworld Hill in English. He first appears to Sol and Sin when they are first attacked by Valentine's servants. Izuna doesn't usually fight, but then reveals that he can fight perfectly well and has much knowledge of magic, much to Sol's annoyance. Like Anji, he appears to be fond of getting information.

Voiced by: Yuji Mikimoto / Michael McConnohie

The leader of a group of animal-type Gears on a remote island called Ganymede. Paradigm is a bird dragon-like Gear who is a brilliant strategist and tactician who also has an immense knowledge of magic. He hates humans at first for their treatment of Gears, but then realizes that not all Humans Are Bastards when he allies with Ky, who makes him the ambassador for Gears in the end.

Voiced by: Chie Sawaguchi / Wendee Lee

The Antagonist of Guilty Gear 2: Overture. She is obsessed with obtaining a certain "Key" that will allow her to enter the Backyard and cause the undoing of the universe. She is completely emotionless, and has eerily robotic mannerisms. She kidnaps and brainwashes Sin for a short period before extracting his DNA, and enters the Backyard. Sol stops the process of the Key turning by destroying it, which causes her to feel her first emotion: PISSED OFF. After her transformations Sol kills her, but not before realizing that she is a clone of Aria, Sol's previous lover.