Spank her ass.

"Okay then Megumin, you're going to like being spanked from now on, and allow it from me or Darkness at any time we want," Kazuma ordered, and Megumin nodded, before blinking again.

"Weird... Why do I keep spacing out?" Megumin wondered aloud, before yelping as a grinning Darkness walked up behind her and gave her ass a slap. "Ah..." she moaned as it registered that she enjoyed it.

"Oi, first honors was supposed to be mine Darkness," Kazuma huffed, crossing his arms at his ****, who looked abashed.

"Sorry Ma- Kazuma," she apologized, barely refraining from calling him Master due to Megumin's presence. "Would you like to spank me some in compensation?"

"That'd just be a reward, and you know it," Kazuma smirked, not as mad as he was pretending to be. "Just wait for my go ahead next time. So Megumin, you want me to spank your ass a few more times?"

"Yes! Er, I mean, sure," she blushed, trying to maintain her dignity.

He chuckled, and then ordered, "Then go ahead and plant your hands against the wall and stick it out."

"Alright," she agreed, walking over and leaning forward, her hands pressing against the wall as she demurely looked back towards him. He walked up and proceeded to slap one ass cheek, and then the other. "Oh!" she gasped in delight. He kept going a couple more times, before nodding to Darkness, giving her permission to join in, and they both took an ass cheek, Kazuma taking the one with the barcode tattoo, and they each gave Megumin a few more slaps.

Megumin panted, but maintained her position on the wall once they had stopped as Kazuma considered his next move.

(So, the meeting with Kyouya should be happening fairly soon... So I'm curious, shall I have Kazuma take his girls after kicking his ass? And if so, in what capacity? Active party members, just side members of his forming harem? I wouldn't mind developing them a bit if it was the former. Please comment your preferences, and I'll take them into consideration.

Edit: I have reached the chapter in question, and pretty much everyone who commented was all for it, so voting is closed!)