User blog comment:B214/Volume 21 info & spoilers/@comment-26821288-20160222182429/@comment-26821288-20160222220154

If only the Volume cover would be a colored illustration of the Lunginus users in their Balance Breaker and maybe also their Breakdown the Beast, and maybe even Vali's JEO, or maybe even some new power-up of Vali, and maybe, even Issei's Cardinal Crimson Promotion, or even Issei's new power-up from Volume 20, Infinity Drive!! There are just so many things in this Volume, that have a lot of potential to be great colored illustration, and maybe even more than the rest of the colored illustrations themsleves.

Although, like B214 already said before, Ishibumi Ichiei did say that he put more effore into writing Volume 21, but no one said that Miyama-ZERO would have done the same, and he probably didn't do the same, which is really unfortunate for us, especially because of this Volume 21 being so amazing. Yet, even with that said, no one said that Miyama-Zero didn't put more effort into the illustrations of Volume 21, so maybe we'll get something (but it's better to keep our expectations down, because DxD has had suffered from a lack of illustrations, already ever since long ago).