Let It All Out.
Definitely the best arc of the series so far. I found Manglobe's free yet judicious use of original scenes and creative content to excellently portray the characters especially Shiori, to an extent I haven't even seen in the manga. I now have much more reason to believe this is all tied in to the manga and I wish the second season manages to continue this.
Also if the image on Keima's PFP at the preveiw is to be believed, I do believe we're getting "that" lecture for the season finale.