If you're looking for anime similar to Kengan Ashura, you might like these titles.
The protagonist, Baki Hanma, trains with an intense focus to become strong enough to surpass his father, Yujiro Hanma, the strongest fighter in the world. Five of the world's most violent and brutal death row inmates are gathering to face Baki. Their objective is to taste defeat -- their unmatched strength and skill have led them to grow bored of life itself, and they now seek out Baki in the hopes that he can overwhelm and utterly crush them. In this crisis, other underground martial art warriors gather to fight by Baki's side: Kaoru Hanayama, Gouki Shibukawa, Retsu Kaioh, and Doppo Orochi. An epic showdown between violent death row inmates and Baki and his friends begins!
Basically it's the exact same genre, underground no holds barred fighting tournaments with a backdrop of vengeance. Also comes with narration to explain moves and techniques.
They both fill the same bare-fisted overpowered martial arts trope so well. I found both of them similar in tone and style. Baki is a bit more coming of age, while kengan is geared a bit older.
Screw power systems and being able to differentiate shounen from seinen. This is pure superhuman martial arts where heightened fantasy meets heightened realism and the path of the fighter is viewed in an almost romanticized light (despite being the first thing the writers of both took very seriously)
A "small" new student, Ushio Hinomaru, appears before the weak little sumo club of Oodachi High School. The words "big" and "heavy" are the rules to this sport, which does not fit this newbie one bit, but Ushio surprises everyone. Ushio and the small sumo club climbs its way to the top with a goal to reach the highest rank, Hinoshita Kaisan.
If you liked Kengan Ashura or Hinomaru Sumo, you'd like the other because both have characters that display their skills in martial arts when they go head to head in matches. And both of the protagonists have the dream of becoming the strongest.
Neither of these shows employ one-trick ponies; characters in both animes display different styles of fighting that aid their victories and come in handy - pun intended - in match after match.
One form of physical fighting is not satisfactory if you are looking for MMA, wrestling, sumo, kickboxing, etc. than these will satiate your appetite. Kengan Ashura emphisizes more mixutue than Hinomaru Sumo but both contain various physical disciplines.
Jin Mori has proclaimed himself the strongest high schooler. His life changes when he's invited to participate in "God of High School," a tournament to determine the strongest high schooler of all. He's told that if he wins, any wish he makes will be granted... All the participants are powerful contenders who fight their hardest for their own wishes. What awaits them at the end of the tournament? A chaotic battle between unbelievably strong high school students is about to begin!
They both have impressively strong characters fighting bare knuckled in an all out brawl. Despite the brutal fighting there is real heart and story to the characters. Yes they want the top title but the fighters also have intelligence
I watched both series expecting some fine hand to hand combat, and both delivered well in that aspect.
The spotlight goes to the fight itself, if that what you are looking the series have well animated and coreographed fights. It was fun and eye pleasing.
One difference is that Kengan has a bit more serious tone.
Yuuya Nomoto, an ordinary college student, met a mysterious high-school student called Hitomi after being involved in an incident, and saw her transform into a beast and fight a Leo monster at a landfill. They're Therianthropes who have brains of humans and fangs of beasts. Hitomi is Ratel, a Brute with the strongest killer instinct. Nomoto gets involved in their battles called Killing Bites.
Mainly, both are about secret high stakes tournament. The other commonality is the contestants in both anime are proxies for corporations. Also, in both anime there is the happless commoner who gets thrown in a high stakes competition as the person in charge of the fighter.
In the world of underground fighting, there is no time limit, no referee, and no ban of technique, not even murderous ones. This is the underground world that Baki, the young champion fighter must fight in to show the world how strong he can be. Only by challenging and accepting the strongest opponents from the world can he hope that one day he can overcome his greatest opponent of all, his father.
Kengan Ashura seems like a tone down remake of Baki, but without the emotional involvement of the characters, the ruthless raw fights and the weirdness of the extreme characters. I rather recommend the original Baki if you like these types of shows. This doesn't even come close.
In a Japanese jail sits 17-year-old Jotaro Kujo: punk, fighter, delinquent...and possessed by a force beyond his control! Around the world, evil spirits are awakening: "Stands," monstrous invisible creatures which give their bearers incredible powers. To save his mother's life, Jotaro must tame his dark forces and travel around the world to Cairo, Egypt, where a hundred-year-old vampire thirsts for the blood of his family. But the road is long, and an army of evil Stand Users wait to kill JoJo and his friends...
MUSCLES MUSCLES MUSCLES!
If you love the sight of bulging biceps, six packs, tight buttocks' and killer intent than these are for you.
Both anime are brimming with exquisite male physiques [females aren't absent but they arent the focus] and physical fight after physical fight.
Both also feature abilities that are more than supernatural.
Crude behavior/language is also present in both but not overrly offputting.
Continuation of Kengan Ashura 2.
It is just before WWII, Kasumi Kenshiro hides as a quiet, absent-minded professor teaching literature at a small women's college in Tokyo. Once the 62nd Grand Master of Hokuto Shinken, "God Fist of the North Star," and known has Yan Wang, or "the King of Death," who preserved the peace in the "City of Devils." A fighter of thugs and drug dealers, Kasumi seeks anonymity and a quiet life until the death of his lover, and former brothers, forces him to return to Shanghai to fulfill his destiny and avenge the deaths of his associates.
Continuation of Fist of the Blue Sky: Regenesis.