Koetsuji Akisame is the philosophical Jujitsu master and doctor of Ryozanpaku who was an old friend of Miu’s father, Fuurinji Saiga. He was also the the first master willing to train Kenichi (though he is the least considerate to Kenichi’s feelings).
Despite his seemingly small physique, he is actually known for having his muscles built to perfection. He also has very good insight on people, often knowing if they are troubled or hiding something; he sometimes even knows what a person is thinking, which scares Kenichi.
He has several hobbies and many unique abilities, including being a famous and legendary artisan, who has mastered calligraphy, painting, pottery, and sculpting. He often invents contraptions that serve as both training devices for Kenichi and power sources for the dojo including a treadmill generator.
He also owns an orthopedic clinic, and can reset and fix bones with ease. It is from his immense skill and knowledge of medicine and anatomy that he developed his unique physical conditioning methods. His skills in the medical field are so great that he was able to save Apachai’s life while the latter had a hole in his side and even using tools from Shigure and performing the surgery on flight, Apachai’s life was saved. He is known amongst doctors as the “The medic demon.” They’re also quite afraid of him.
He seems to hold some kind of grudge against Takeda’s master James Shiba as seen when James often insults Akisame’s mustache. This grudge held to the point of a rivalry of some sorts as the two actually bet their mustaches to be shaved should the losers disciple lose the match.