User blog comment:B214/Volume 23 discussion blog/@comment-30924344-20170401231420/@comment-30924344-20170402000527

You know what I think. That S4 might be announed at the end of the airing Deadly Sins. Because he's being going on a lot of business trips at the same time Sins has been in production and it just so happens that 3 of the voice actresses for DxD have had a role in Sins. Now, I believe, at the same time, those actresses have been voicing their roles for S4 and that Artland and TNK have been pooled together some budget for S4. Ishibumi has been out at the same time the actresses should be working and if this was not the case, Ishibumi would have no reason to go on these business trips; if Season 4 was going to have to wait for the actresses to finish with Sins. It's also coincidental that TNK are helping make Sins with a company that has more budget than TNK. So with that, I believe Ishibumi has been going to meeting with these 2 companies and pre-producing S4 to air after Sins and that they will use the budget of Sins to make a S5 as Artland does have enough money [just see the anime they worked on here to see why: https://en.wikipedia.org/wiki/Artland_(company)#Works], to help fund it with the money that will be gained from Sins. Well this is just what I hope might be the case.