It's a shame the oni girl isn't in the WN though, makes me feel like shes only going to be tacked onto the story. I'm liking her more now though, I hope the story has had a lot more of her added in.
Wait is the contract: [Don't tell on MC] <-> [We can leave]
So she went out of her way to let him know she's keeping it secret (and knock out some dudes) so she can win affection points?