Speed of Sound Sonic is the foremost antagonist of One Punch Man.
AboutHe was ninja who declared himself as Saitma's rival is first hired by Mr. Monier as bodyguard defending him from a group calling themselves the Paradise Group including leader Hammerhead who is terrorist and cowardldy man. when Saitima and his partner Genos came the scene approaching Sonic. Who fought them. Saitima breaking Sonic's sword, biting it. Subsequently, Sonic beat Hammerhead and his boss Mr. Monier. Saitma tried explain to Sonic that he was hero who worked hard to defend the city but Sonic wouldn't listen
Sonic was arrested and quickly sent to the prison but manages to break out several times by escaping it, he defeated prisoners who tried killed him.