Kunio (くにお) is one of the two main protagonist of River City: Tokyo Rumble.
- Hair Color: Brown
- Eye Color: Brown
- Height: 175 cm (5'7")
- Weight: 65 kg (143 lbs)
- Blood Type: AB
- Status: Alive
- Affiliation: Nekketsu High School (Southside High School in Crash 'n the Boys: Street Challenge)
- Year: Sophomore (Nekketsu Kouha Kunio-kun series), Senior (Downtown Nekketsu series)
- Alternate Names: Mr. K (Renegade), Sam Powers (Super Dodge Ball), Alex (River City Ransom), Jeff "Crash" Cooney (Crash 'n the Boys: Street Challenge)
- Hobbies: Dodgeball, Football, Hockey
He serves as the famous guardian of Nekketsu High School against rival schools and is the captain of the school's Dodge Ball team. A righteous delinquent with a strong personality, he has a heart of gold and cannot abandon those who are in trouble. He has a weakness for pretty girls, which often leads to heartbreak.
Although he is the captain of the Dodge Ball club, he excels at other sports and participates in many of the other sports clubs at his school as an assistant, where he displays ace-class skills that exceed the capabilities of regular club members.
Kunio's best friend and rival is Riki Samejima, the banchou of Hanazono High School. After joining forces in Downtown Nekketsu Monogatari, the two are always seen working together as allies against a common threat, but they continue their rivalry in multiple sports competitions.
River City: Tokyo Rumble is the direct sequel to Nekketsu Kouha Kunio-kun Special.
Tokyo as been relatively peaceful after Kunio's defeat of Sabu. Sabu promised Kunio that he would keep his hands off the country. Leaving Nekketsu High School with Misako, Kunio sees Sakata, Wataru and a knocked out Hiroshi. After making sure he is okay, Kunio runs after Sakata and Wataru to get revenge. After he defeats them both, he learns from Sakata that Riki gave the order to beat up Hiroshi. Kunio travels to Shinjuku to confirm, and Riki makes it clear that the two are being played. Riki agrees to settle the matter back in Ikebukuro. While in a vacant lot there, the two meet Ginjishi, a member of the Kanto Lion Alliance, which plans to take control of Tokyo. Sakata and Wataru have joined the alliance as well. After defeating all three, Kunio and Riki agree to join forces to stop the Kanto Lion Alliance.
When starting a new game, Kunio is the only character the player controls, just like in the previous game. He has no special moves, but can learn every special move in the game, unlike the other characters. In the game's Rumble Mode, he can use the Mach Kick and the Whirlwind Kick, while he uses his trademark Nuts Shot and Penetrating Shot in the Dodgeball Mode.
- In Renegade, Kunio was changed to a nameless vigilante who had to rescue his girlfriend from a gang of thugs. The NES version of the game gives him the name Mr. K.
- In the NES version of Super Dodge Ball, Kunio was named Sam, a captain of Team USA.
- In River City Ransom, Kunio is known as Alex. His full name is expanded to Alex Kun in River City Ransom Underground.
- In Crash 'n the Boys: Street Challenge, Kunio was named Jeff "Crash" Cooney, a captain of Team Southside High School.
- He is named after Technos Japan's former president, Kunio Taki.
- Kunio has no surname. The closest he has had to a surname is Oyama, due to second Oyama brother in Double Dragon 3: The Rosetta Stone being named Kunio. In the TV drama, he is given the surname Fu'unji (風雲児).
- Kunio is the only character whose name was not mixed up in Nintendo World Cup.
- Kunio's birthday is on November 27, the same as Bruce Lee. Kishimoto choose this date in order to pay homage to Lee.
- Kunio can be considered Nekketsu High's Banchou (番長), a Japanese term used to call the leader of a juvenile delinquent gang. This can be noticed due to the fact most of his schoolmates often look up to him (examples include Hiroshi and Sugata), and is always the captain of the Nekketsu High sports team in every respective game. Also, the typical image of a banchou is an uncouth fighter who has a strong sense of honor.
- The character Yusuke Urameshi from the anime and manga series Yu Yu Hakusho bears a resemblance to him.