Kendo Rappa/Synopsis

History
Kendo used to spend his days fighting in an underground fighting ring. He did this as a rebellion over his strict parents. In that fight club, fighters could go berserk with their Quirks. Kendo's battle prowess made him too powerful for all his opponents and he never got the death-match he always desired.

At some point, Overhaul attends a fight to recruit Kendo to join the Yakuza. Kendo tried to kill him and ended up "dead" himself, or so he thought. Overhaul used his Quirk to repair Kendo's body.

Kendo joined the Shie Hassaikai with the sole intent of fighting Overhaul. He has been killed all five times he's challenged Overhaul.

Shie Hassaikai Arc
During the raid of Overhaul's hideout, Kendo is paired with Hekiji. When Joi Irinaka launches Fat Gum and Eijiro into another room, Hekiji and Kendo are already waiting for them. Launching a barrage of punches, Kendo manages to break through Eijiro's Red Riot Unbreakable. Taishiro tries to punch Kendo, but Hekiji protects his partner with a Barrier.

Kendo complains when Hekiji stops him from attacking Taishiro, to which Hekiji reminds him that Overhaul paired the two up because their Quirks have great synergy. Kendo replies by trying to attack Hekiji, which he blocks with his Quirk. A confused Hekiji asks Kendo what he is doing, to which Kendo replies that he does not care about Overhaul's plans and that he only wants to kill. Hekiji decides to let him do as he pleases, while also reminding him to address Overhaul properly.

As Taishiro prepares to fight back, Kendo orders Hekiji not to interfere, to which Hekiji assures him that he will not. Upon seeing Eijiro's fear, Hekiji notes that he has already given up and expresses pity for the young hero. After Kendo is done assaulting Taishiro, Hekiji notices that Taishiro is preparing for another counterattack and tells Kendo to finish things quickly. As Kendo tries to finish Taishiro off, Eijiro interferes, taking his attacks and attempting his own counterattack; however, Hekiji blocks it with a barrier. Hekiji simply notes how meaningless it was for Eijiro to take these attacks.

Soon, however, he realizes that Eijiro's actions were not in vain as Taishiro emerges from the dust and releases all the impact he stored from Kendo's punches with a single powerful blow. Hekiji however creates a barrier with maximum defense that absorbs most of the impact, which prevents the two from being knocked out. Kendo stands up again and claims that it is a fight to the death and he is not dead yet. He asks Taishiro to take Eijiro to the next room with first-aid supplies. Hekiji questions the selfish attitude of Kendo and demands that he follow his orders, but Kendo knocks out Hekiji by stomping on his chest and declares that he wants a fight to the death against Eijiro.

After treating Eijiro's injuries, Taishiro asks about Kai's plan and the reason Kendo is following him, so Kendo tells him that he is only around to defeat Kai someday and that Kai wants to reinstate the Yakuza. After Kai's defeat and Eri's rescue, he was apprehended by Juzo Moashi and arrested.