User blog comment:SpookyBoogie27/Light Novel Spoilers/@comment-37.231.114.51-20130209171033/@comment-33447191-20130209224857

Yeah it's titled " The Decision of the Student Council" (Issei joining the Student Council) although I believe that it's only temporary. Here's the summary:

Saji gets sick with dragon-flu so Ise took his position temporarily. Published in Dragon Magazine, it is not yet collected in the published novels. Dragon-flu is a type of flu that only happens to dragons and people possessed by dragons. The Student council needed man power which meant either Issei, Gasper or Kiba. Gasper was rejected instantly because he won’t be considered as manpower. Sona chooses Issei. Rias tells Sona to take Kiba instead, but Souna said that a couple of girls won’t be able to work seriously if Kiba joins. They’ll get too distracted with Kiba. - (Taken from Animesuki)