Accelerate

Speed-o'-Sound Sonic drops from a streetlight, bragging that he will finish Genos and take Saitama next, while Fubuki reads his killing intent and calls him dangerous. Genos volunteers to deal with Sonic, who mocks his sluggishness, prompting Genos to accelerate and flash behind his foe, though Sonic reacts and slips the strike. Watching alongside Fubuki, Saitama notes that Genos is faster than during their own sparring and guesses he has upgraded his components, while Fubuki can barely track the pace.

Annoyed at Genos repeatedly materializing behind him, Sonic feels mocked, and Genos shears off his topknot, leaving him with short hair and fresh anger. Genos moves in with Machine Gun Blow only to discover he has hit an afterimage, and Sonic answers with his secret Four Shadows Burial, Scattered Flash Slash, too swift for Genos to trace. Genos prepares to torch the whole area at full output. Just as Sonic seems poised to win, Genos suddenly drops, felled not by the enemy but by Saitama, who stopped his disciple to keep him from wrecking their nearby neighborhood. Saitama declares that Sonic's true quarry is him and resolves to take the fight seriously, and Sonic vows to use the ultimate technique he devised to kill him.

Relieved to be overlooked and aware she could have been in real peril, Fubuki keeps watching. Sonic strikes with Ten Shadows Burial, which Genos and Fubuki barely follow, but he gains no advantage. Saitama counters with a killer move, Serious Series: Serious Side Hops, spawning countless clones that overwhelm Sonic. Sonic appears knocked out, and Genos briefly thinks him dead before he vanishes in an instant. Having seen it all, Fubuki concludes Saitama is simply too strong.

Genos duels Sonic at high speed and slices off his topknot before Sonic escapes his Machine Gun Blow with an afterimage. Saitama fells Genos to stop him from destroying the neighborhood and takes over the fight. Saitama's Serious Series: Serious Side Hops overwhelms Sonic, who escapes intact, leaving Fubuki awestruck at Saitama's power.

This Volume 9 chapter continues the Blizzard Group Arc and adapts into Episode 14. Its cover assembles Saitama, Speed-o'-Sound Sonic, Genos, and Fubuki. It corresponds to Chapter 49 of the webcomic and was released in three parts between February and March of 2015.