"Speed-o'-Sound Sonic is a character appearing in the Japanese manga series ""One-Punch Man"". He is a villain who wields an incredible speed and agility, making him a formidable opponent for the series' protagonist, Saitama. Sonic is known for his arrogance and disdain towards others, especially towards Saitama, whom he sees as a mere obstacle to his goals.

Sonic is a highly skilled assassin, recognized as one of the best in the world. His speed is his primary weapon, able to move so quickly that he appears in multiple places at once. Despite his incredible speed, Sonic has shown to be more than just a one-trick pony, utilizing his skills in martial arts and wielding weapons such as shurikens and katana blades.

Despite being a villain, Sonic has shown to have moments of honor and even friendship towards others. He has worked with Saitama on several occasions, albeit under duress, and has even formed alliances with other villains when it suits his purposes.

Sonic's obsession with defeating Saitama has often led him astray, causing him to underestimate his opponent and be outmatched time and time again. However, Sonic remains undaunted, continuing to train and improve his skills in the hopes of one day defeating Saitama and claiming his place as the world's strongest.

In conclusion, Speed-o'-Sound Sonic is a dynamic and complex character in ""One-Punch Man"". He is a skilled and deadly assassin with an arrogance that clashes with his moments of honor and loyalty towards others, making him a fascinating addition to the series."