After a nuclear war, societal norms collapse. Ken, a peacekeeper, battles lawlessness, haunted by his sister's death. Facing tyrannical rule, he embodies Zen, seeking to reform himself and his foes through training and resolve.

In a post-nuclear world, Ken, a wandering disciple under the tutelage of a master, finds himself ensnared by a former foe before being rescued by a mysterious savior. Invited into a territory governed by three ruthless rulers-a drug-addicted boss and two volatile mid-bosses-Ken witnesses the tyranny plaguing the land. After a failed attempt to thwart the brutality of the mid-bosses, Ken escapes and seeks training from his distant master, who imparts upon him the wisdom of Shorinji Kempo. As Ken hones his skills and grapples with personal loss, he matures into a formidable warrior. Returning to confront his adversaries, Ken faces off against the first mid-boss, "Sake Kasu Man," employing his newfound prowess to emerge victorious. Despite enduring a grueling duel with the second mid-boss, armed with a deadly samurai sword, Ken triumphs through sheer determination. Concerned for Ken's safety, his master dispatches a direct disciple to aid him. As Ken challenges the boss, he finds himself outmatched and injured. Yet, in a moment of clarity, Ken unveils a special technique, toppling the boss and inspiring awe in all who witness his prowess. Recognizing Ken's embodiment of Zen principles through his actions, the boss acknowledges his transformation. In a poignant finale, Ken bids farewell to the territory's inhabitants, symbolizing hope for a brighter future as he faces his master's disciple. With a symbolic gesture, Ken casts a crushed red spider lily into the sky, signifying the dawn of a new era.