Manga by author Saruwatari Tetsuya - Status ongoing

From Viz:Nobody enjoys a good fight more than "Kiibo" Miyazawa, a high school student whose father is training him in the family's secret martial art. Kiibo dreams of becoming the next Bruce Lee, but his awesome fighting skills may soon surpass his idol's!

The story is set in a dystopian near future where the Japan society is experiencing a crime rampage and in which a powerful and secret religious organization, with mysterious goals, is acting as an invisible hand behind the scenes.The main character is their strongest assassin, lent to them by his fanatic mother when he was a child, and now a ruthless killing machine whose fists and feet cause serious damage to his adversaries, and whose weapon of choice is a special cutting wire with which he grabs and scorches his opponents.He's a man hunter, whose childhood has been stolen and molded after his tormentors, but when the road of forgiveness is precluded to him what can be left to a man to obtain the redemption?Takeo finds the answer in the vengeance, and in eradicating that same evil from which he has born.So this dark and impressive badass guy, after betraying the sept, gets down to business kicking their ass and unleashing his fury against the deadly opponents sent to stop his unparalleled revenge.

The series starring one of illegitimate children of Kiryu Miyazawa, Ryuusei Nakamura. Years after Kiibo founded the new dojo, both him and Kiryu mysteriously disappeared. Ryuusei, after losing his mother to cancer, is set to find out about his birth father and his destiny as the evil dragon's heir, but he is not the only one.