His nickname is "Mach Punch Riki". The inspiration for the Mach Punch comes from the Speed Racermanga (which was known as Mach GoGoGo in Japan). Animating the Mach Punch in the original arcade game (when Riki grabs Kunio and punches him) reminded Kishimoto of the Mach GoGoGoanime Kishimoto on the Mach series of attacks.
According to Yoshihisa Kishimoto, Riki's name originates from a notorious yakuza in his youth.
The character Kazuma Kuwabara from the anime Yu Yu Hakusho bears a close resemblance to him due to his Pompadour hairstyle and his uniform color.
In Nekketsu Kōha Kunio-kun, Riki's surname was Hibari. Samejima was introduced as his surname in Downtown Nekketsu Monogatari. However, according to Yoshihisa Kishimoto, Riki is simply named Riki Kishimoto on Riki's surname (Japanese)], just like the rest of the characters that debuted in Nekketsu Kōha Kunio-kun ([./https://kuniokun.fandom.com/wiki/Wataru_Sasaki Wataru] is one exception). It is unknown if Riki is his surname or given name.
Kunio's catchphrase, "Namen'nayo!" (なめんなよ!, roughly translates to "Don't mess with me!"), originated from Riki in the original arcade game as well as in the Famicom version. He originally said "Namen'nayo kono yarou!" (なめんなよ この やろう!, roughly translates to "Don't mess with me, punk!").
Riki shares many traits with Kunio, such as his roughed up appearance and his deep sense of honor. Unlike his rival, however, he has a more serious, quiet and down-to-business personality, as noticed in [./https://kuniokun.fandom.com/wiki/Shin_Nekketsu_K%C5%8Dha:_Kunio-tachi_no_Banka Shin Nekketsu Kōha: Kunio-tachi no Banka] where he's the character that speaks the least.
