Speed-o'-Sound Sonic/Other Media

Prison
As Sonic became a villain, he is quickly taken to prison, but manages to break out several times, often in the blink of an eye, until the guards are forced to put him in restraints and send him to the maximum security Smelly Lid Prison. There, he effortlessly defeats the prisoners who dare to challenge him, even causing one to scream out in pain, which in turn causes the "boss", Puri-Puri Prisoner to shout at the other prisoners in irritation. After listening to a description of Puri-Puri Prisoner, Sonic then witnesses his breakout due to watching the Deep Sea King's rampage on television; recognizing his strength, he follows the man out of the prison.

Catch & Smash
Sonic encounters Saitama in the K-City Nature Park and challenges him to a fight once more. He tries out his new equipment against Saitama and initially it seems to work. However, once again, Sonic loses when Saitama accidentally elbows him in the groin and he lets Sonic go again.

Confidence
Following on from Speed-o'-Sound Sonic's decision to eat a monster cell, Sonic has diarrhea for the whole night. After the ordeal, Sonic believes he has become a monster and that while, he has not changed his appearance, his body has undergone a massive change. He has vindictive thoughts about Gale Wind and Hellfire Flame for not telling Sonic about the diarrhea. However, he puts the thought aside as he never planned to join the Monster Association, he feels great power within himself. Feeling lighter and more powerful, Sonic is brimming with confidence and states he will need time to adjust to his new body. In reality, Sonic just lost 2 kg from his diarrhea and is mistaking his condition as his new monster form.

The Ninja Who is Too Complicated
After losing against Saitama, Sonic begins having nightmares and flashbacks of the incident. He confides his worries to a matagi, who consoles him about his fears. As Sonic is training, he saves a small baby boar, who he later names Ino and together with it, trains to become even stronger. He regains his confidence, and after defeating Saitama in his visual training, he decides to leave, saying farewell to the matagi, who later corrects him about his name. Sonic later silently watches over the city, ready for his next battle.

Puri-Puri Prisoner and the Jailbreaking Prisoners
One stormy night, a monster emerges from a junkyard and begins making its way towards Smelly Lid Prison, where Sonic is located. Noticing its approach, Puri-Puri Prisoner breaks out of his cell and quickly defeats the monster. However, he damages the prison's electricity in the process, allowing a handful of inmates to escape. Sonic notices the commotion and confronts Puri-Puri Prisoner, with his shuriken ready for a fight, asking why he didn't try to bring him back too when he escaped during the Seafolk attack. Puri-Puri Prisoner reveals that Sonic was strong enough to escape without his help anyway, and tells Sonic he has a place back at the prison for him before leaving with the inmate. Sonic scoffs at the offer.

Zombieman Murder Case 2
Speed-o'-Sound Sonic is training on a mountain when he notices Saitama, who happens to be spending the night in a lodge on the very same mountain. Sonic decides to hunt Saitama, however, he stays outside in the blizzard for too long and freezes, losing his balance and crashing through a window. Saitama and a group of S-Class heroes restrain him, but Sonic still plans to kill Saitama. Sonic easily escapes the ropes and tries to attack Saitama from under the floorboards, but is stopped by Genos, and their encounter destroys the room. The dust irritates Saitama's nose, and he sneezes with enough force to blow open every door and window in the lodge. The power goes out, followed by a sudden explosion. The heroes grab a flashlight and head to the den, finding the room destroyed and Zombieman unconscious. Sonic proceeds to claim he is innocent. Eventually, a monster crashes through the front door - however, he is quickly defeated by the abundance of S-Class heroes and Sonic.

Sonic, Becoming Saitama
Sonic challenges Saitama to another match and Sonic experiences his 11th loss. Frustrated over his lack of progress against Saitama, Sonic decides to experience life as Saitama in order to uncover his weakness. Sonic disguises himself as Saitama, imitating his looks and speech patterns. Genos comes across Sonic and mistakes him for Saitama. Sonic lies about encountering a monster that hit his head, making his memory foggy and forgetting Genos' name. Genos is shocked and asks where the monster is to which Sonic replies it ran away into the mountains. Genos leaves to give chase to the monster and kill it.

To understand Saitama further, Sonic heads towards the Hero Association. There, he encounters Kamikaze. Kamikaze questions why Sonic is there and is annoyed at Sonic's attitude. Sonic draws his blade but Kamikaze blocked it with his sword with such speed that Sonic didn't even see the blade being drawn. Tatsumaki enters the room and berates Sonic as she is annoyed that a weak B-Class was summoned for the mission. Sonic, not understanding who Tatsumaki is, believes that she used her cuteness to make it into S-Class. Tatsumaki demands Sonic leave which he does with his smokescreen shuriken leaving her and Kamikaze coughing.

Sonic, angry over his experiences so far, wonders that perhaps Saitama is suffering horrible treatment he receives from the public. A monster called Angry Grandpa kidnaps a child. Mumen Rider arrives a delivers a Justice Tackle to free the child and a Justice Punch and Justice Kick followed by a Justice Crane High Kick. Sonic saves Mumen Rider from a powerful attack and they finish off the monster. Mumen Rider thanks Sonic for his help and Sonic asks why he is a hero since he almost died. The child gratefully thanks Mumen Rider and Sonic for saving him. Mumen Rider decides to contact the Hero Association to collect the monster. Mumen Rider leaves, suggesting they go drinking sometime.

Sonic understands why Saitama decided to become a hero but not his strength. As Saitama battles monsters on a daily basis, Sonic decides to see if he can uncover the secret of his strength in battle. Sonic comes across Energiser who he recognized from the secret documents he stole from the Hero Association. He informs Energiser that Tornado of Terror and Atomic Samurai are hunting him and that he plans to take him down by himself. They engage in battle. Despite his skill, Sonic loses the battle and almost dies if it weren't for the timely arrival of Saitama.

Together they take down Energiser. Saitama's questions Sonic' attire and asks if he wants to be a hero. Sonic says he doesn't want to be a hero and that he knows Saitama's weakness. Once more, Sonic declares that he will end Saitama's life. Sonic then leaves with a final message saying that Saitama will soon know his weakness. Sonic then decides that he was tired playing hero and that as long as he is fighting monsters, Sonic won't attack Saitama. He once again decides that the only way to beat Saitama is to hone his skills further.

Junior high school student Saitama Episode 3
Sonic transfers to Z Municipal Peace Middle School to settle a dispute with Saitama. Currently, there is a sports festival. Sonic, who wanted to beat Saitama, has gotten on the same team as him and struggles to win.

One Punch Man: A Hero Nobody Knows
Speed-o'-Sound Sonic is a playable character in the video game, One Punch Man: A Hero Nobody Knows.

Grand Summoners
Sonic is one of the various characters able to be summoned. He is no tank, but dodges most damage headed his way. He supports his allies via defense and crippling damage on foes, and has lots of equipment available.