User blog comment:DeathGodPrayer/Talk About What You Want!/@comment-50.11.177.49-20121125181436/@comment-33447191-20121226132945

It's actually part of a side story titled "Let’s Go to Onsen!"

It could be included as one of the short stories in Volume 15 of the Light Novels, but I'm not sure.

It was actually finished not too long ago. You can read it here: http://shincodezeroblog.wordpress.com/highschooldxd/short-stories/dragon-magazine/lets-go-to-onsen/

(Courtesy of Code-Zero/ n0m@n)