Saitama vs. Speed-o'-Sound Sonic

Saitama vs Sonic (F-City) is the first battle between Saitama and the assassin Speed-o'-Sonic.

Battle
After defeating Hammerhead, Sonic attacks Saitama mistaking him for a paradiser. He then tries to kill Saitama for being able to keep up with his speed. He showcases his speed and tries to attack Saitama with his wind blade kick but is accidentally hit in the crotch by Saitama ending their fight.

Aftermath
While writhing in pain Sonic declares Saitama his rival and declares he will one day kill Saitama.