Gokuaku no Hana

is a manga authored by Sin-ichi Hiromoto that was published in the Weekly Comic Bunch from 2008 throughout 2009 and republished in a two-volume collected edition. It is the fourth spinoff of the Fist of the North Star manga by Buronson and Tetsuo Hara published by Comic Bunch. The manga centers around the childhood of the villainous Jagi, the third and often-neglected of the so-called Hokuto Brothers from the original work, as his seeks to pursuit the art of Hokuto Shinken and make his adoptive father proud of him.

The second volume also includes the one-shot story Hokuto no Ken Ryuken Gaiden - The Judgment Day (北斗の拳リュウケン外伝　THE JUDGEMENT DAY), originally published in the January 8, 2007 issue of Comic Bunch, which focuses on Ryuken's whereabouts on the day of the Nuclear War.

Plot
Before the Nuclear War, before he took his brother Kenshiro's name and attempted to tarnish his reputation by committing various acts of violence at innocent people, Jagi was nothing more than an average boy who wanted nothing more than to earn the appreciation of his adoptive father Ryuken. One day, Ryuken suddenly brings two older boys (Raoh and Toki) to live with Jagi, who are being trained in Ryuken's martial art of Hokuto Shinken. Feeling left out and rejected, Jagi does everything possible to convince Ryuken to teach him the art as well. When Jagi finally becomes Ryuken's newest disciple, he learns that Kenshiro, a boy younger than himself, has also become Ryuken's disciple before him.

Characters

 * Jagi (ジャギ) - The protagonist of the manga. The third of the Four Hokuto Brothers. He was orphaned as an infant when he lost his real parents during a fire and thus, was adopted by his rescuer Ryuken. He is initially raised by Ryuken as an ordinary son until he is introduced to his elder adoptive brothers, Raoh and Toki, who are being trained by Ryuken in the ways of Hokuto Shinken. Not to be left out, he convinces Ryuken to take him under his wing as well. When he becomes Ryuken's latest pupil, he realizes that Kenshiro, a boy younger than him, has already been chosen to be Ryuken's disciple before him. As a result, he develops a severe inferiority complex and starts
 * Anna (アンナ) - A female member of a biker gang who becomes acquainted with Jagi during a chance meeting, she is one of the few people who Jagi opens up to and can cheer him up.
 * Ryuken (リュウケン) - The 63 Grand Master of Hokuto Shinken and Jagi's foster father. He originally raised Jagi and choose not to train him in the ways of Hokuto Shinke due to his profound attachment to him. When Jagi convinces him otherwise, their relationship changes from father and son to master and student.
 * Raoh (ラオウ) - The eldest of Ryuken's students for the Hokuto Shinken succession. Has strong ambitions and openly despises both, Ryuken and Jagi.
 * Toki (トキ) - The second of Ryuken's students. A gentle character who often shows concern towards both, Kenshiro and Jagi.
 * Kenshiro (ケンシロウ) - The youngest of Ryuken's students and the protagonist in the original manga, who eventually becomes the 64 Grand Master of Hokuto Shinken. He becomes the target of much of Jagi's fury, due to the fact that Ryuken already chose him as a student before Jagi, despite being the youngest.
 * Boss (ボス) - Anna's elder brother and the leader of his own biker gang.
 * Masked Gang (マスク団) - The rivals of Boss and Anna's gang, who usually wear skull-shaped masks.

List of volumes

 * Volume 1: ISBN 978-4-10-771478-7
 * Volume 2: ISBN 978-4-10-771509-8