Iwao Oguro vs. Kendo Rappa

Iwao Oguro vs. Kendo Rappa is a battle fought between the Pro Hero O’Clock, disguised as the The Ripper, and the underground fighter The Rapper.

Prologue
O'Clock has been investigating the trafficking of uppers and Quirk-boosting drugs for quite some time, and their investigations led them into the world of underground fighting. In order to infiltrate that world and continue with his investigation, he becomes The Ripper, an underground fighter specialized in knife combat and who does not need to use his Quirk to win, achieving five victories and no losses.

His success in fights opened the doors to a masked fighting tournament known as the Underground Masquerade, a safe haven fighting ground for anybody willing to wear a mask. That place is one of the main distribution centers for the Quirk-boosting drugs, since many of the undergrounds fighters dope themselves with the enhancing substance for the fighting. To obtain some evidence, O'Clock decides to participate in the illegal tournament and calls Detective Eizo Tanuma and the police to back him up, to assure him of an escape route once he has obtained what he was looking for and then break up the illegal event. With everything ready, O'Clock disguises himself as The Ripper and goes inside.

Once in the underground arena, the ring announcer introduces him to the viewers as The Ripper, then, he introduces who will be his opponent, the unstoppable human being with 20 wins and zero losses, Kendo Rappa, here known as The Rapper. Before the match begins, Kendo complains that both he and his opponent have similar stage names, which makes things a bit confusing. He also complains to The Ripper for using a knife, telling him that if he wants a real fight, he must fight like a real man, without weapons, like him. The Ripper taunts him asking if he's afraid of him and his knife, but he denies it and encourages him to come at him, knife and all, as he sticks with his code.

Battle
As soon as the bell rings, Rappa attacks Iwao with an onslaught of punches thanks to his Strongarm Quirk. For the spectators and for Rappa himself, it looks like The Ripper can barely defend himself against the brutal strikes and is thrown violently against the barriers of the fighting cage, losing the mask and knife in the process. Actually, it was all an act on Iwao Oguro's part.

Knowing that his prep as The Ripper the Knife Fighter has not use against a fighter like Rappa, Iwao decides to change strategy and fight like a street brawler. Using his Overclock Quirk, Iwao intensely focused his senses to avoid the worst blows. Since the knife would only slow him down, he decided to take advantage of Rappa's attack to get rid of the weapon, making it looks like he was disarmed as a result of Rappa's punches. He also decided to do the same to get rid of the mask, because he needs to breathe better to be able to use his Quirk properly.

After the murderous rush, Iwao stands up, declaring to Rappa that he had a soft spot for simple guys like him. The announcer is impressed that The Ripper endured the brutal flurry of blows, but since he isn’t unscratched and he is unarmed, he considers his only option is to admit defeat. To his surprise, The Ripper says he keeps going. Iwao looks at Kendo and smiles, stating that since he's a nice guy, he's going to play by his rules and fight weaponless. Rappa is happy to hear that and praises him, as he pounces on him to continue the fight.

Rappa unleashes another onslaught of violent blows on Iwao, who returns to use his Overclock Quirk to defend himself from it. Despite his opponent's crude fighting style, Iwao cannot find an opening even with his Quirk activated. However, he was not there to win that fight but to further investigate the organization behind the Underground Masquerade, so he decides to end the battle.

Choosing the right moment, Iwao feigns getting hit by Rappa and falls to the ground. The referees enter the ring, and after checking that he is "unconscious", they declare The Rapper the winner of the match.

Aftermath
The "unconscious" The Ripper is taken to another room to be "healed". A mysterious guy congratulates him despite his defeat, and plans to inject him with a substance that will help him win the next fight.