The Yama-Sen Ken (山千拳 Yamasenken?), translated variously as 1000 Mountain Path, Mountain of 1000 Fists, and Way of the Noisy Thief, was one of two secret and deadly styles of martial arts that Genma Saotome developed when he was younger, the other being the Umi-Sen Ken. However both styles were so destructive that they were later sealed away.
While both styles used the analogy of the human body as a house, they were originally intended for robbery and burglary. The Yama-Sen Ken's techniques specifically simulated the forced entry of a robber through the front door and emphasized "strength", utilising brute force and broad moves. When Genma came across the Kumon Dojo, which was collapsing, he gifted the scroll containing the Yama-Sen Ken to Ryu Kumon's Father out of compassion, intending for the man to rebuild the dojo. However while practicing the techniques on the dojo itself, the elder Kumon inflicted such structural damage on it that it collapsed and killed him. Giving the scroll to his son Ryu, he enjoined him to find the Umisenken scroll. Ryu pursued this solitary mission for the next several years, knowing only that the scroll was held by the Saotome family.
Ryu by chance arrived in Furinkan, where he saved Nodoka Saotome from a bear that had broken loose from an exhibit. He dropped the scroll by accident and Nodoka picked it up, noticing that it had her husband and son's names on it. When he told her that his name was Ranma Saotome, she believed that she had been reunited with her son as she did not know what Ranma now looked like. Ryu briefly began staying at the Saotome home where he searched for the Umisenken scroll, but could not find it. However his deception had been seen by the real Ranma, who called him out that same night. The two briefly fought, but Ranma was distracted by Nodoka when she came out to investigate the noise caused. He nearly fell to Ryu, but was saved by a smoke bomb thrown by Genma. Ranma then learned that his father had created the Yama-Sen Ken.
The Yama-Sen Ken is the most brutally direct of the two "sibling" styles, and is arguably the style best suited for direct combat usage thanks to its powerful attacking skills.
Should a Yama-Sen Ken master fight an equally skilled master of the Umi-Sen Ken, then barring outside interference or unusual circumstances, the Yama-Sen Ken master will always lose, as the Umi-Sen Ken was created specifically for countering and defeating the Yama-Sen Ken.
- Opening move: The user shouts something distracting at the opponent, such as "Freeze!" This can severely disrupt them or even freeze them in their tracks, making them susceptible to follow up attacks.
- Fierce Tiger Gate-Open Blast (猛虎開門破 Mōko Kaimon Ha?): A dual strike akin to forcing open a door and crashing through. The user spreads his arms apart in an opening motion while simultaneously kicking with one foot. Ryu used this to knock out a rampaging bear and save Nodoka Saotome.
- Crushing Embrace of the Killer Grip (懐中宝珠殺 Kaichū Hōju Satsu?): A powerful bear hug, strong enough to break an opponent's back.
- Deadly Snake-Pit Probing Palm (毒蛇探穴掌 Dokuja Tanketsu Shō?): A fierce strike to the chest area in an attempt to literally rip out an opponent's heart. It would have taken out Ranma the first time had not Genma intervened by throwing a smoke bomb to allow him to flee.
- Flight of the Tight-Bind Golden Threads (金絲緊縛翔 Kinshi Kinbaku Shō?): Ryu throws a rope around his opponent to bind them and allow them to be reeled in.
- Fanged Fingers of Steel Welcome-Gate ( 迎門鉄扇指?, Geimon Tessen Shi): A powerful strike with all fingers extended. This took Ranma out during the second fight.
- Demon-God Multiple Strike (鬼神来襲弾 Kijin Raishū Dan?): Simulating the action of flinging shutters open, the user's movement are so swift that the air itself is forced apart, creating a vacuum of sharp blades of air capable of cutting through even metal.
- Violent Dance of the Demon-God Horde (鬼神群大乱舞 Kijin-Gun Dai Ranbu?): The second ultimate technique. Similar to the Demon-God Multiple Strike, with the user spinning to fire off multiple bladees of air at random.
- Ultimate Demon-God Multiple Strike (最大級鬼神来襲弾 Saidaikyū Kijin Raishū Dan?): The most powerful version of the Demon-God Multiple Strike.