User blog comment:Xhatefate/DxD Updates~/@comment-16281343-20150518234334/@comment-16281343-20150520172821

Looks like the other titles from the leak are also placed on honto.

"富士見ファンタジア文庫 7/18日発売 ●ハイスクールD×D20 ●空戦魔道士候補生の教官7 ●ゲーマーズ！2 ●ロクでなし魔術講師と禁忌教典4 ●おまえをオタクにしてやるから、俺をリア充にしてくれ！12　大学生編"

So, I guess we can pretty much count that this one is legit? 18 -> 15 isn't a problem as there are other cases like that. (example: v14 is listed 1/18 there but the actual date is 1/19)

What bugs me out are
 * the similarity of 20's title (進路相談, Career Consulation) to 14's (進路指導, Career Counselling). Does Ishibumi not have any other idea?
 * Though, fwiw, 14 is Ravel's, 20 has Ravel in the middle of it all.
 * the summary is really really bare compared to the past Volumes. There's nothing you can get out from that. The summary can be basically created from "Top Secret".
 * I just hope we will have another summary when other sites post their v20 page.