Kunou Ryuushin was the fourth generation head of The Front of Armament. The younger brother of Kunou Issei and Kunou Hideomi, who was the corrupted head of the third generation of T.F.O.A., Ryuushin was his vice-head, until both him and his brother were defeated by Bouya Harumichi.
He later becomes head of the fourth generation and reestablished the Armament as one of the toughest and most honorable gangs in Toarushi.
Acknowledged as one of The Four Kings in his generation, Ryuushin is a fearsome fighter and has displayed very impressive technique over the course of the series, utilizing a boxing style which makes him one of the most dangerous opponents to go up against.
As a former vice head, Ryuushin has a cool head on his shoulders and because of his stoic personality, he rarely loses his cool, preferring to let his fists do the talking.
Joining The Armament
Ryuushin was recruited by his older brother Kunou Hideomi and served with his brother under the second head of The Armament, Sugata Kuzushi.
It is not known if he disrespected Sugata like his brother but Sugata seem to acknowledge Ryuushin's strength by saying that if Ryuushin and Bando would join up together then they would make one hell of a team.
Ryuushin seems to acknowledge Bandou strength, as seen when he asked his brother if he would take Bandou with him to a fight. His brother said you would have to be crazy to take Bandou with you, but Ryuushin is seen thinking if you had asked me, implying he would take Bandou with him.
When the second generation head, Sugata died, he became the third generations Vice Head under the third generation head, his brother, Hideomi.
Fight with Bitou Tasuya
Ryuushin arrived at a meeting with his brother and saw the fight between Bitou Tatsuya and two officers named Kitagawa and Hirota. When Kitagawa and Hirota were defeated by Tatsuya, Ryuushin stepped in to fight. Ryuushin was already consider a strong fighter, so it surprised everyone that Ryuushin was defeated  and that the fight was so one sided.
After his defeat at the hands of Tatsuya, he started showing up less and less to the Armament meeting causing his brother to become nervous and recruit more men.
Fight With Suzuran
He is next seen in a meeting with the rest of the Armament leaders and his brother, Hideomi, talking about Mito's defeat at the hands of Bouya Harumichi. He is ordered by his brother to go with Iwai, and Anzai, and attack Bouya's Faction. He fights both Hiromi Kirishima and Pon at the same time and defeats them both . When Harumichi and Makoto Sugihara show up to fight the Armament, Ryuushin gets angry because he feels that Harumichi is looking down on the Armament. He also says that Harumichi is doing this to have an excuse for when they lose . He then attacks Makoto and beats him and then turns to fight Harumichi telling him that he will beat them both and that they will be known as the saddest most pathetic guys that ever existed . He and Bouya started fighting and Ryuushin is beating up Bouya until he trips on a rock and Harumichi takes advantage and choked him out, leaving everybody in the Armament stunned that he lost because they saw him as being invincible .
Days later, when The Armament goes for their final attack against Harumichi, Ryuushin is seen in The Armament warehouse with his brother and his brother's thirteen elite guard holding Yasuda as a hostage and waiting for Harumichi. He watch as Harumichi fights with the thirteen elite guards and notice that Harumichi was holding back so that he would have enough strength to fight Ryuushin and Hideomi . Ryuushin has conflicting thought because he is waiting to fight Harumichi but Harumichi is fighting thirteen other people and even if he beats Harumichi he cannot call that actual victory. He acknowledges that no matter how it happened he still lost to Harumichi before. He also acknowledges that the way the Armament fights is wrong because Harumichi is fighting the Armament by himself while the Armament attacks people in groups.
When he sees that the Suzuran students have scared away all the Armament members that where waiting outside of the warehouse he tells Hideomi to go out the back and orders the only two guards left to go with him . He prepares to fight all the Suzuran students just like Harumichi did with the Armament. All the Suzuran's students get ready to fight him but Harumichi yells at them and calls them jackass saying that they are not The Front and that he will fight Ryuushin by himself. Before the fight Harumichi tells Ryuushin that they don't gang up on people like bitches at Suzuran  and that Suzuran and the Armament don't matter. Ryuushin just wants to settle the score with him and calls Bouya a bastard . They start fighting with Ryuushin dominating the fight just like the previous fight. Ryuushin then yells at him that he deserves that for underestimating him.
Harumichi then tells Ryuushin that he has a habit of trying to beat people with the same style they fight with  but he is going to stop because he just getting beat up and they start fighting again. The fight becomes more even and they go back and forth. Harumichi gains the upper hand and trips and bangs Ryuushin's head on the floor over and over but Ryuushin gets up bloodied and Harumichi just push him and Ryuushin falls . When the two TFOA elite guys came back to check up on Ryuushin, he tells them he lost and that Harumichi is on a whole another level and that all he can do is laugh .
Fight at The Gokoku Shrine
Since the defeat of his brother, Ryuushin has taken over The Front of Armament as the new head.
Before Bulldog fight at the Gokoku Shrine, Ryuushin mentioned when they were talking about who was the strongest in the city. They say that even though he lost to Harumichi, he is still a contender for the strongest.
He is next seen when he is driving on his motorcycle with his two friends (the two guards from the warehouse) when he is stopped by Harumichi, who asks them if they are going to see Bulldog fight and then asked them for a lift . Ryuushin smiles and tells him to get on and they drive to the Shrine. On the way there, Harumichi falls asleep and the other two tell him to throw him off .
When Bulldog was about to lose, Harumichi yells at him to get up and everyone's surprised to see Ryuushin and Harumichi together . Akira then asked Shingo if Ryuushin and Harumichi are blood brother too. Ryuushin then asked Harumichi if he has become blood brother with Bulldog and Harumichi says yes because Bulldog is something else .
Fight with Teru
Ryuushin and his two friends are stuck in a garage area waiting for the rain to end before riding home. His two friends went to get coffee and he waits for them . They were attacked by two guys from out of town .
The next day he looks for Takeshi and Tsuyoshi. He finds them and described the guys to them and asks if they know who the two guys are . They tell him that they are Teru and Kiiko. When Harumichi asks Ryuushin if he was going after those two he say yes, because they greeted his guys last night . Ryuushin finds them before the Kurotaki Alliance does and says that he was looking for them because they attacked his guys . Teru tells him that he was the one who beat them. Teru threw a kick at Ryuushin but he dodges and Ryuushin throws a punch at Teru and he dodges. Ryuushin is surprised that Teru dodged his punch meanwhile Teru asks if Ryuushin is part of the Kurotaki Alliance he tells them that he is part of The Front of Armament and Teru decide to call the fight off . Ryuushin says that he can't stop the fight because they were the one who started this. Teru tells him that if he still hasn't changed his mind after they are done with their fight with the Kurotaki Alliance then Teru will fight him  which Ryuushin said he will look forward to it. Teru asks him his name and he tells him, Ryuushin of The Front of Armament. Teru asks if is anybody like him in the Kurotaki Alliance. Ryuushin tells him he don't know but there are two guys that they should avoid (referring to Harumichi and Rindaman) .
Teru went to search for Ryuushin after his fight with the Kurotaki Alliance is over and Ryuushin welcomes him . Ryuushin's subordinates tell him that he picked the joker in fighting Ryuushin. Ryuushin tells his subordinates to stop arguing with Teru and gets ready to fight him. They start fighting and Ryuushin tells Teru that he is not a bad fighter . Teru tells Ryuushin that he is not a joker if he is any of the thirteen card, he is a king or and ace but Teru and his friends truly is a lonely Joker . Ryuushin tells him that, that just sounds like he needs a friend and that they will talk after they are done fighting . They continue fighting and it seem that Teru have the upper hand but Ryuushin tells him that he lost and gains the upper hand knocking Teru down. Teru get up and says he can't lose but gets knocked out by Ryuushin who tells him he lost . Ryuushin waits for Teru to wake up and asks Teru if he would like to be blood brothers with him. Teru accepts by shaking Ryuushin's hand .
Ryuushin is next seen sitting by the river bank reading a letter written to him by Teru. The letters tells him that he can't stay and join the armament because he can't leave behind his friends, but he won't forget that he has a friend in that city and if Ryuushin needs him he will be there to help him, he also tells Ryuushin to visit him. Ryuushin comments on having a brother in a city far away and says that it pretty cool. He is caught by surprise by Pon and Hiromi asking if that is a love letter he is reading and he tell's them it not what they think. Hiromi sees Ryuushin smiling ask Ryuushin if even he can smile. Ryuushin responds that he is not a robot and that he smiles when there is something worth smiling about. He asks them how Harumichi is doing and warns them that some of his guys have seen Housen skinhead around here. He tells them even though the Kurotaki Alliance is around Suzuran is still top dog around these parts, and there are people trying to make there names by taking out Suzuran's head. He told them to tell that to Mr. Peaceful all day, referring to Harumichi.
Suzuran vs Housen
Ryuushin is seen at the Junkyard with his two subordinates talking about Harumichi defeat at the hand of Housen . Ryuushin is seen thinking why Housen would attack the head of Suzuran, Harumichi because it didn't sound like something Machida, Kunimoto, and Kikuchi would do implying that he knows them somehow. He wonders if there is somebody else running .
He snaps back to reality when he hears that Bandou has gone back to Suzuran. He tells his subordinates that Bandou has more spine than they are giving him credit for. He also wonders what Bandou's next move will be .
Ryuushin is mentioned again when Bandou tells the story of how Ryuushin was defeated at the hands of Bitou Tatsuya when they first joined The Armament. Everyone was surprised to learn this and Yasuda can't believe that Ryuushin whom Harumichi acknowledges to lose so badly .
Harumichi vs Rindaman
Ryuushin is seen waiting at the Gokoku Shrine with Teru and Kiiko who came with him to watch the fight between Harumichi and Rindaman . Teru and Kiiko get into an argument with Maru and Kaku because Maru and Kaku didn't know that Teru and Kiiko were the duo the Kurotaki Alliance was fighting against.
Ryuushin tells them to take it easy but then notice Tatsuya and they exchange words and stared at each other until Rindaman showed up and quiets everyone.
As he watches the fight between Harumichi and Rindaman he is surprised when Harumichi knocked Rindaman down. While the fight continues he is amazed at how strong Harumichi is, because of how many of Rindaman's punches Harumichi has taken and is still able to keep fighting.
He watches as Rindaman defeats Harumichi and Rindaman carries a unconscious Harumichi away after there fight is over.
A couple of days after the fight he is seen saying goodbye to Teru and Kiiko as they head back home.
Ryuushin invited Bouya Harumichi to help Kiiko and Parko after Teru was stabbed by one of Snake Heads' members . Afterwards Tatsuya Bitou ended up joining the group and the group was known as P.A.D (Parko and Dangerers) was brought to life.
He moved to Tokyo and started a career in professional boxing. Later, Bitou Tatsuya would also move to Tokyo and going professional in the same gym as Ryuushin, as they kept their rivalry.
He won his professional boxing debut with a knockout in the first round .
- Ryuushin vs. Hiromi, Pon - Won 
- Ryuushin vs. Mako - Won 
- Ryuushin vs. Bouya - Lost 
- Ryuushin vs. Bouya - Lost 
- Ryuushin vs. Teru - Won 
- Ryuushin, Kitagawa, Hirota vs. Tatsuya - Lost 
- Ryuushin vs. Fujita - Won 
- Ryuushin vs. Sasazawa, Mita, Minami - Won 
- Ryuushin, Tatsuya vs. Murakami Kazuhiro, Iijima Nobuhiro, Motohashi Masayoshi - Won 
- Ryuushin vs. Ooshima Tomoyuki - Won