|Nickname||The Monster's Monster|
|Age||40s to 50s|
|Family||Seiko Miyazawa (Twin-Brother)|
Yumiko Miyazawa (Older Sister)
Son-O Miyazawa (Older Brother)
Kiichi Miyazawa (Adoptive Nephew)
Marcio Naito (Son)
Various unnamed children
Ryusei Nagaoka (Son)
Garcia’s clones (Sons)
Kiryuu Miyazawa (宮沢鬼龍, Miyazawa Kiryū) is one of the main antagonists of the series. He is considered as the incarnation of the devil by anyone who has met him. He is more of an anti-hero type as he constantly pushes Kiibo to surpass his limits.
Unlike his brother, Kiryuu is wicked and completely ruthless. He is also an intellectual that quotes philosophers, appreciates art, and read many books even when hospitalized. But this is only another facet of his ruthless nature, because Kiryuu values mental and physical strength above all else.
Kiryuu looks almost exactly like his brother Seiko, since they are identical twins. The only exception being that Kiryuu has slicked back hair, a scar across his face and he doesn't wear glasses.
He has superhuman endurance. Kiryuu has been able to fight with severe physical injuries, including gouged eyes, crushed throat and broken arm. Kiryuu possesses the physical condition in his legs called the Dragon's Foot (Japanese:
Kiryuu possesses extensive command of the martial arts, specifically the Nadashinkage-ryuu. His proficiency is such that he is both revered and feared, internationally and within the most criminal circles.
- In the side story Tough Gaiden: Oton, it is revealed that Kiryuu fathered a child with the daughter of the United States President.
- Kiryuu can play the piano.
- He managed to train a kangaroo, the animal manage to win a fight in a boxing match.