When Onogi said he was going to fight fair and square only with the help of his strength, you bet he was serious. They were three minutes into the fight and Onogi had not used any of his scientist shit.
He had planned to play fair, but Hitori had not. Still, Hitori refrained from using magic– it would be a one-shot if he misses, he is dead– so he held onto his chance.
So he had cracked Hitori's jaw with two punches on the jaw and one on the chin. He was holding onto the pain somehow. After five minutes, Hitori realized he has fighting experience but not outside of the game.
Outside of the game, he is just another nerd with the talent for gaming and a brain for plotting– not with the strength for executing. I just need to get her out of here and kill his bastard somehow.
He was buying time. Hitori dodged another punch but did not bother to land a punch in Onogi's abdomen. He would have stopped the punch anyway, though.