Genos vs. Speed-o'-Sound Sonic

Genos vs. Speed-o'-Sound Sonic is a fight fought between Genos and Speed-o'-Sound Sonic.

Prologue
Genos is with Saitama at their apartment, when he feels someone coming towards them. While checking outside, he discovers Speed-o'-Sound Sonic. Sonic claims to be Saitama's rival and wants to fight him. Not wanting to disturb his master, Genos challenges Sonic himself.

Battle
They begin their battle and are shown to be on equal footing, with Sonic being too fast for Genos, and Genos being too durable. They continue fighting for 20 minutes, and as Genos tries to attack Sonic, the impact accidentally catches Fubuki in her fight with Saitama. Genos apologizes to Saitama for the damage and recognizes Fubuki, misinterpreting her position as a failed attempt at taking down Saitama, when Sonic attacks Genos with his Exploding Shurikens, which prove to be ineffective. Sonic declares that he shall defeat Genos and challenge Saitama to another duel, but Genos simply states he will make sure Sonic will be erased. Sonic, amused by Genos' statement, is suddenly attacked, surprised at the cyborg's speed. Genos attacks with his Machine Gun Blows, but Sonic manages to dodge the cyborg's blows. Genos sprints up to him and attempts to attack with a right punch, but Sonic manages to dodge the blow again. The two continue fighting, while Sonic continues to dodge, albeit with difficulty. As this continues, Sonic wonders why Genos keeps on appearing behind him. Sonic is infuriated that Genos thinks he's faster than him, and Genos tells him that he had some lint in his hair, which is actually the top knot of Sonic's hair that Genos cut off. Sonic is enraged by the cyborg's impudence, and Genos uses this opening to attack Sonic with his Machine Gun Blows, but he is surrounded by Sonic's Four Shadows Burial. This technique creates multiple afterimages which Genos cannot track. Just as Sonic is about to attack Genos with his Scattered Flash Slash, Genos decides to blast the whole area with his Incineration Cannon, but is knocked down by Saitama, who didn't want his place to be destroyed.

Aftermath
Saitama intervenes in the fight, scolding Genos for not having any reason to fight Sonic. Saitama then decides to fight Sonic seriously, to which Sonic declares he will show his newly developed technique.

Manga and Anime Differences

 * In the anime, the battle between Sonic and Genos lasts for 20 minutes before Fubuki arrives.