Kendo Rappa met Overhaul for the first time when he appeared one day out of nowhere in the underground fight club. He wanted him to join Shie Hassaikai and challenged him. Kendo was not interested and fought against him, but he was easily defeated by Overhaul, so he had to join the Yakuza. Since then Kendo has challenged Kai five times and has lost to him five times. 
Unlike the other seen members of the Eight Bullets, Kendo does not seem to fully respect Kai. This is shown when he openly declares his disdain for him after Overhaul forced him to partner with Hekiji based on their Quirks, and the reasoning behind it, preferring to fight on his own rather than rely on the "Spear and shield" plan they were given. He also does not refer to Overhaul properly, calling him "Overjerk" instead.
Kendo doesn’t care much for Overhaul's goals or ambitions, openly revealing them to Fat Gum, seemingly unconcerned with the repercussions for committing such an act.
Overhaul brought Hekiji into the Shie Hassaikai since his Barrier Quirk served to control Kendo's thirst for battle. Kendo does not appear to particularly like Hekiji, though he works with him out of necessity.
Clashing with his calm and calculative nature, Kendo dislikes Hekiji for attempting to restrain him when it comes to battling. He will even go as far as to attack Hekiji when he prevents him from getting a fight that he desires, or even when he tries to stop Kendo from displaying his own brand of honor.
Kendo Rappa didn't hesitate to step on Hekiji to knock him out when he wanted to help Fat Gum and Eijiro after his defeat.
Kendo met Fat Gum when he was removed from the raid by Mimic along with Eijiro Kirishima. Kendo began to appreciate the hero when he challenged him to fight him without relying on Hekiji's barrier. Kendo is glad Fat Gum understands his desire for battle and accepts the challenge, encouraging him throughout the whole fight not to die too early against his attacks.
Although he and Hekiji were defeated by Fat Gum thanks to the intervention of Eijiro Kirishima, Kendo respects Fat Gum for his guts and tells him where there is an aid room to treat his wounds and Eijiro's. He was also very honest with him and told him everything he knows about Overhaul and his plans.
Like Fat Gum, Kendo meets Eijiro during the Heroes’ raid on the hideout after Mimic separates him and Fat Gum from the main group. He manages to damage Eijiro's hardened state by blowing him into the wall with his punches. Before Kendo could land his finishing blows on Fat Gum, Eijiro used himself as a shield and withstood the attacks, leaving Kendo impressed by how he was still standing.
After he and his partner Hekiji are defeated by the BMI Hero, Kendo reveals that there are some first aid supplies in another room and tells him to heal Eijiro as he wanted to have another fight to the death with him, showcasing how much respect he has gained for the young hero for his unyielding resolve and dedication.
- ↑ 1.0 1.1 1.2 1.3 1.4 My Hero Academia Manga and Anime: Chapter 146 and Episode 73.
- ↑ My Hero Academia Manga and Anime: Chapter 144 and Episode 72.
- ↑ 3.0 3.1 3.2 My Hero Academia Manga and Anime: Chapter 143 and Episode 72.