He was one of the sensei, or teachers, at the Niten Ichi Ryu. He taught kenjutsu, the Way of the Sword, and is Masamoto's rival in a sense, having fought him in a long lasting duel which had to be stopped due to the destruction they have caused. After they ended in a stalemate, Hosokawa asked Masamoto to teach him the Two Heavens technique, and the two founded the Niten Ichi Ryu. He dies protecting Sensei Yosa from the enemy forces in The Way of the Dragon.
In the first book Sensei Hosowaka is seen as a strong sensei that made no allowance for mistakes. His first lesson was to "defeat the sword" where they had to hold their swords out without dropping it. Jack passed this lesson succesfully outdoing Kazuki. In the swordfighting round in the Taryu Jiai, Sensei Hosowaka gives valuable advice to Jack which enables him to ultimately draw with Yamato. Sensei Hosowaka was also there when Jack, Akiko and Yamato got their rewards.
In the beginning of this book, Sensei Hosowaka teaches jack the meaning of his sword by telling him to slice a grain of rice on Yamato's head with the sword having the capability of killing Yamato. In the circle of three, Sensei Hosowaka's trial was the gauntlet where Jack came to the end but did not realize that he had to battle Sensei Hosowaka and was struck down. However, despite this error, Sensei Hosowaka passed him. While training Jack, he introduced to Jack the concept of mushin. After The Circle of Three, when Jack is battling Sasaki Bahaman, Sensei Hosowaka told Jack how to use mushin, which enabled Jack to defeat Sasaki Bishamon. Along with Masamoto and Sensei Yamada, he learns the secret of the rutter.
In The Way of the Dragon, Sensei Hosokawa is killed in the battle of Osaka Castle whilst defending Sensei Yosa after she was shot by an arrow. Out of respect for Sensei Hosokawa protecting Sensei Yosa with his life, she is spared and is presumably held captive by Kamakura.
He is a fierce looking warrior with jet-black hair and dark piercing eyes. He also has a beard, a petrifying typically Japanese looking split beard. It is rumored he sets his beard on fire to scare away enemies in battle and in the heat of the combat, boost his adrenaline by 150%.
Jack -His star student. Sensei Hosowaka always has a tip or a way to guide and help him in the way of the sword.
Masamoto Takeshi - Friend and former rival. These two interact with each other and are partners in teaching the Two Heavens techique. Theyre equally skilled in swordsmanship and have yet to end their duel with a victor.
Kenjutsu master- Sensei hosowaka is one of the best swordsman in japan known for defeating his opponents mind. He is certainly an extremely skilled and experienced swordsman, being one of the very few people who can fight on par with Masamoto Takeshi.
Two heavens- Sensei hosowaka is a master in the two heavens technique along with masamoto. This technique is said to make one invincible
Mushin- Sensei hosowaka is also an adept in mushin where the mind becones"no mind" and the sword becomes "no sword"
Resilience- He is also extremely resilient, physically. In The Way of the Dragon, when surrounded by swordsmen, Hosowaka battled them - even though he was repeatedly pierced by arrows, he continued to fight them off.
Sensei Hosowaka is seen as a strict teacher who expects his students to come on time,dress smart and prosper in the way of the sword. However, he is a very good teacher who guides all his students and helps them throughout. He was extremely brave, and willing to fight off an overpowering enemy that he knew he couldn't defeat, if it meant allowing his friends to survive.