I think it's more like "nice slow mo detail of the fist punching the manjuu and sending it fly away" than a "nice reflex from the manjuu"
You know like those flicks on which they go ubber slow-mo when someone is hitting, kicking or throwing someone and you could swear you hear the slow-moish voice going "NOOOOOOOOOOO-BLAMMO"
Hmm no matter how much i see it, while i know it's clearly the yukkuri getting decked, i can't help but feel we are missing a panel, maybe one of the yukkuri "flying" away from the fist but the fist still visible?