Kenichi: The Mightiest Disciple

Initially, his motivation is self-preservation and a desire to overcome his weakness. This quickly evolves into a powerful drive to protect his friends and especially Miu. He adheres strictly to the philosophy of Katsujin-ken, believing that martial arts should be used to save people, not to harm them. This moral conviction becomes his primary motivation, giving him the strength to face opponents far more powerful than himself.

Kenichi's arc is a classic zero-to-hero journey. He begins as a timid, physically weak high schooler who prefers reading self-help books to confrontation. His initial motivation is simply to stop being bullied. Upon joining Ryōzanpaku, he is subjected to inhuman training that slowly forges him into a capable fighter. His arc is defined by his struggle to overcome fear. In early fights, he is often terrified, but his courage grows as he finds things worth protecting—his friends, Miu, and his moral code. He evolves from someone who fights out of necessity to a true martial artist who actively stands up for justice, all while retaining his kind and gentle nature.

Miu is motivated by a deep-seated kindness and a sense of justice. She has a strong desire to protect the innocent and has a particular fondness for kittens. She is also driven by her love for her grandfather and the other masters at Ryōzanpaku. She supports Kenichi's training because she sees his good heart and believes in his potential to become a true protector. Her primary motivation is to live up to the legacy of her family while also finding her own place in the world.

Miu is introduced as a seemingly perfect martial arts prodigy, possessing immense skill from a young age due to being the granddaughter of the dojo's Elder. However, her arc reveals her own vulnerabilities. Having moved frequently and been isolated with martial arts masters, she is socially awkward and struggles to make normal friends. Her relationship with Kenichi helps her open up and experience a normal school life. While she is always Kenichi's superior in skill, her arc involves learning to trust others and finding a balance between her life as a martial artist and a regular teenage girl.

Hayato's motivation is to preserve true martial arts and counter the dark influence of the Satsujin-ken philosophy. He gathered the masters at Ryōzanpaku to create a bastion for his ideals. He is also deeply motivated by his love for his granddaughter, Miu, and his desire to see her safe and happy. He sees Kenichi's potential not just as a fighter, but as someone worthy of carrying on their legacy and, potentially, of being with Miu, famously declaring Kenichi can only marry her if he can defeat him.

Known as the "Invincible Superman," Hayato is the legendary elder of Ryōzanpaku who has never lost a fight. His arc is that of a seemingly untouchable figure who takes on the responsibility of guiding the next generation. While his power is absolute, his character is revealed through his interactions with Kenichi and Miu. He is kind and grandfatherly, often apologizing to Kenichi for the harsh training, yet possesses a reckless and arrogant streak. His arc is less about personal growth and more about imparting his wisdom and ensuring the philosophy of the "life-saving fist" is passed down correctly.

Akisame is motivated by the pursuit of perfection in all things, whether it be art or martial arts. He believes in the harmony of mind, body, and technique. His primary motivation as a teacher is to mold Kenichi into a true disciple of the Katsujin-ken, not just by making him strong, but by making him wise. He takes a profound and personal interest in Kenichi's development, seeing him as his most challenging and rewarding creation.

Akisame is the first master to seriously train Kenichi and serves as his primary mentor in strategy and philosophy. A master of Jujutsu, he is also a polymath skilled in sculpture, calligraphy, medicine, and engineering. His arc is one of a patient and insightful teacher. He understands Kenichi's weaknesses better than anyone and designs his training specifically to overcome them. While always a master, his interactions with Kenichi show his deep commitment to the nurturing of potential, believing in a scientific and philosophical approach to martial arts mastery.

Sakaki is motivated by the spirit of a true fighter. He seeks worthy challenges and respects strength and courage. Initially, he has no interest in teaching, but he is moved by Kenichi's unwavering determination. His motivation becomes to see his disciple grow into a man who can stand on his own, often placing bets on Kenichi's success as a gruff way of showing his faith in him.

The 100-dan Karate master, Sakaki is initially reluctant to train Kenichi, viewing him as a weakling. His arc is about warming up to his role as a teacher and developing a strong, almost paternal, bond with Kenichi. He is often depicted as short-tempered, loves to drink and gamble, and quarrels with the other masters. However, beneath his fierce exterior lies a deeply caring individual who consistently shows up to protect Kenichi when he is in mortal danger, often giving him crucial advice about the realities of a fight.