That Man, who's real name is Asuka R. Kreuz, is the unseen instigator of all the events in the Guilty Gear series. Nobody knows exactly who he is, but he seems to be very powerful. He was one of the discoverers of the magical science, and the deviser of the Gear Project, thus being the creator of the Gears. Because of it, He is often referred to as the "Gearmaker".
He used a man named Frederick as the prototype for the Gears. Frederick would later become Sol Badguy and seek revenge against That Man, pursuing and destroying all the Gears. Most of the cast of Guilty Gear is after him for some reason, be it for revenge or because of his great knowledge about just everything in the world.
It isn't know exactly what are his goals, but he seems to be repenting for having created Justice, and is seemingly luring everyone to prepare them for a plan he has for the world, which involves the insurgence of a new threat greater than Justice. He has three henchmen: Raven, I-No, and Jack-O, all three of them are assisting him in his plans. He also recruited the help of Anji-Mito, in exchange of telling him everything he knows about everything. He has also created a isolated structure within the Backyard, known as the Cube. With it, he can potentially manipulate and reshape the laws of the universe to his whim.
Asuka's face and body are never seen and is usually covered in cloaks. However, one artbook showed him with a pure white hair and a normal build. However during the day when he was with Freddick (Sol) and Aria (Justice) he had white hair. In 'Guilty Gear Xrd: Revelators he reveals his young true appearance which confirms his white hair, blue eyes with a eyepatch on the right one, an inverted red cross design on his bangs and pointy red ears.
- It is revealed in his official short story that he's been slowly reversing his age. His voice sounded like a middle aged man in Accent Core while he seemed to be much younger in Guilty Gear 2: Overture.
- Sin and That Man share the same English voice actor Yuri Lowenthal, who also voiced Patroklos.
- Ironically, as of the Revelator ending, Sin's face is similar to That Man, which is the reason why Sol had been treating Sin badly for his annoyance has anything to do with Sol and That Man's past friendly rivalry on arguing each other's problems.
- Izanami the antagonist of the BlazBlue series is That Man's counterpart but they have only a few differences.
- They both have hidden agendas that involve manipulating the protagonists and exploiting their power. However, as of Overture where That Man revealed to be good all along, he is now more of counterpart of Rachel Alucard.
- They both punish their minions albeit in different ways: That Man punishing I-No for her antics and Izanami betraying Yuuki Terumi and Relius after they stop being useful to her.
- He also seems to value his minions on somewhat of a personal level and they feel complete loyalty towards him and his goals—even I-No. Whereas Relius and Terumi are merely tools to Izanami, and they in turn have their own machinations in store.
- That Man seems to seek atonement for his sins and prevent the world's prophesized annihilation while Izanami wants to make a world of death and decay.
- That Man is a human scientist and mage with modifications while Izanami is a goddess.
- That Man's role actually similar to Rachel's.