ONA
Description
Goki Shibukawa, often referred to as the Master, is a prominent character known for his mastery of aiki and jujutsu. Physically, he presents as an unassuming elderly man, standing at 155 centimeters tall and weighing only 47 kilograms, with grey hair and a slim build that starkly contrasts with the heavily muscled figures that are common in the series. He is around 75 years old and his left eye is a prosthetic, a consequence of an injury suffered in his youth.

Shibukawa's personality is a blend of calm composure and a fierce, combative spirit that emerges when provoked. Despite his aged appearance, he is belligerent and unforgiving towards opponents, often speaking to them with harsh swears or curses. He possesses a twisted and comedic side, frequently using deception and psychological manipulation during fights, such as pretending to be a frail old man in need of a bathroom break, only to launch a sudden attack. He has a traditionalist’s strict attitude towards martial arts, believing one should always be ready for a real fight and never warming up before a duel, yet he is pragmatic enough to use any means necessary to win, including headbutts. He typically looks down on younger fighters but has shown the capacity to develop respect for those who prove themselves.

His motivations stem from a lifelong dedication to martial arts and a genuine love for fighting. In his youth, he was a ruthless fighter who joined the army and killed for fun. This bloodlust drove him to even challenge his own master, Kihei Mikoshiba, with deadly intent. This encounter was formative, leading Shibukawa to eventually surpass his teacher and establish his own style, Shibukawa-ryu Jujutsu. His primary motivation in the story is to test his skills against worthy opponents and prove the effectiveness of his techniques, which focus on using an enemy's power against them.

Within the narrative, Shibukawa plays a significant role as a legendary figure in the underground fighting world. He participates in the major tournaments, serving as a major obstacle for other fighters. His most notable early achievement was defeating the powerful karate master Doppo Orochi in the quarterfinals of the Maximum Tournament, a victory he attributed to his longer period of training. He ultimately lost in the semifinals to the monstrous Jack Hammer, a defeat that left him acknowledging that his opponent was on a different level. Despite his age, he continues to be an active and respected fighter, later engaging in spars and matches against other top-tier combatants like Biscuit Oliva and Mohammad Alai Jr..

Key relationships further define his character. His bond with Doppo Orochi is particularly noteworthy; he initially dismissed Doppo as an amateur but developed a deep respect for him after their intense fight, even expressing a desire to live another ten years just to face fighters like him. He also forms a friendly yet competitive relationship with Baki Hanma, who acts as his second for a match. A significant figure from his past is his master, Kihei Mikoshiba, whose teachings about perfect self-defense—a state where the subconscious prevents a fighter from entering a truly dangerous situation—greatly influence Shibukawa's approach. Interestingly, Shibukawa's own body subconsciously manifested this principle when it created terrifying visions of a cliff and a massive sealed door to try and prevent him from walking into a fight with Jack Hammer, sensing the immense danger.

Shibukawa’s development throughout the series shows a man who has mellowed from his youthful, bloodthirsty days into a seasoned master, yet he has not lost his core combative nature. His arrogance has been tempered by defeats and hard-fought victories, allowing him to acknowledge the strength of others.

His notable abilities are centered on his mastery of aiki, a principle that allows him to redirect an opponent's force back onto themselves, meaning a stronger attack results in an even more powerful counter. This technique makes him incredibly dangerous, as he can throw or disable much larger and stronger opponents with minimal effort. Other signature techniques include the finger-grab, where he immobilizes an enemy by seizing a single finger, and more pragmatic attacks like spitting a stream of water into a vital point on an opponent's face to disorient them. He is also skilled in using pressure points to paralyze or incapacitate foes. Despite his small stature, his skill and decades of experience allow him to stand as an equal among the world's mightiest fighters.