"That man" is a character that appears in the "Guilty Gear series".
One of the masterminds in the "Guilty Gear Series", the person who created the biological weapon GEAR, which is the key to the story. Speak in a gentle and atonement tone. Its existence is recognized as a great sinner who created gear by the general public (the birth of gear followed the rebellion of Justice = the holy war, and developed into the Hundred Years War between Gear and humankind). Very few people know their real names, and many are commonly known as "that man." From "Guilty Gear 2", the scenes called "Gear Maker" have increased. Although he has lived for over 150 years, he is a human being, not a gear. Sol says, "In the human bullet battle, it is a level that can be defeated by the old man in that area, but it is the top as a wizard," he said, saying the strength of "that man."