User blog comment:B214/Question and Answers 2/@comment-187.195.197.49-20140501191827/@comment-16281343-20140501234130

The correction isn't on the story itself but on the synopsis that was posted in the kadokawa website, but it isn't that big of a deal so they won't probably change it.

~The collaboration was on the DxD card game. There were some pics in the animesuki forum of ikkitousen characters on the card game. There's even a pic with Rias and Hakufu together.

~There's also a part there about Kiba, Tsubaki, and Gram. There should have been a scene in Volume 17 about Kiba according to the quotes and synopsis about 17, right? But he wasn't able to put it in because of his health condition. So, if I read it right, Kiba's part will be on 18.