This story is fictional but based on the experiences the author Matsuda Ryuuichi had and the people he met, researching and training Chinese martial arts (CMA). Kenji and his experiences are sort of idealised version of Matsuda and his experiences. It's one of the most realistic representations of CMA in fiction that I've come across.
Li Shuwen is quite central in the story although he's been dead for decades before the actual story starts. Kenji's grandfather and various other people tell Kenji stories about Li Shuwen (Li Shobun in Japanese). He was known for having countless challenge matches, never losing and almost never striking more than once. The last volume is a kind side story of sorts, telling a story of Li Shuwen's life.
Some of the real-life characters who appear in the story (given names have been changed in the manga):
Liu Yunqiao (Ryuu Unshou) with the sunglasses, Li Shuwen's student
Su Yuzhang (So Ikushou) the small man with the mustache, Liu Yunqiao's student
Zhang Shizhong (Chou Shichou) old man in Chinese restaurant in Yokohama, grandstudent of Li Shuwen
Overall the most informative manga on martial arts I've yet read. The author falls to the same trap as most Japanese martial art stylists and tries to systematise CMA too much. The principles are explained well, yet the result is a bland and static expression of the arts, something clean but useless. Someone once said that Matsuda seems to be a better mangaka than he is a martial artist. Well, it's obvious that he is more the "scholar-type" than the "warrior-type". Nevertheless just as important and much more influential, having started the "Baji-boom" in Japan late 80's.
Having gone to find the "home of Bajiquan" and finding a place that had ceased to be so a long time ago and bringing in the limelight a small branch of Baji and making them into the "original", just as placing the hybrid Wutan Baji style as the successor of Li Shuwen's lineage and starting the Baji-boom in Japan making Bajiquan the most common CMA in Japan after Taijiquan, one can see how this is not just another manga but an actually influential piece of modern literature.
However that may be, it's an effort to applaud to.